1
|
Shiels A. Through the Cat-Map Gateway: A Brief History of Cataract Genetics. Genes (Basel) 2024; 15:785. [PMID: 38927721 PMCID: PMC11202810 DOI: 10.3390/genes15060785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 06/06/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
Clouding of the transparent eye lens, or cataract(s), is a leading cause of visual impairment that requires surgical replacement with a synthetic intraocular lens to effectively restore clear vision. Most frequently, cataract is acquired with aging as a multifactorial or complex trait. Cataract may also be inherited as a classic Mendelian trait-often with an early or pediatric onset-with or without other ocular and/or systemic features. Since the early 1990s, over 85 genes and loci have been genetically associated with inherited and/or age-related forms of cataract. While many of these underlying genes-including those for lens crystallins, connexins, and transcription factors-recapitulate signature features of lens development and differentiation, an increasing cohort of unpredicted genes, including those involved in cell-signaling, membrane remodeling, and autophagy, has emerged-providing new insights regarding lens homeostasis and aging. This review provides a brief history of gene discovery for inherited and age-related forms of cataract compiled in the Cat-Map database and highlights potential gene-based therapeutic approaches to delay, reverse, or even prevent cataract formation that may help to reduce the increasing demand for cataract surgery.
Collapse
Affiliation(s)
- Alan Shiels
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| |
Collapse
|
2
|
Ozler O, Egeli BH, Zeybek S, Eris E, Teke Kisa P. A Novel Homozygous GALK1 Variant Combined With Cataract and Prolonged Jaundice. Clin Pediatr (Phila) 2023; 62:537-540. [PMID: 36411586 DOI: 10.1177/00099228221136120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Oguz Ozler
- Division of Pediatric Endocrinology & Diabetes, Department of Pediatrics, Washington University in St. Louis School of Medicine, USA
| | - Bugra Han Egeli
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Selcan Zeybek
- Department of Medical Genetics, Tinaztepe University Faculty of Medicine, Izmir, Turkey
| | - Erdem Eris
- Department of Ophthalmology, University of Health Sciences Dr. Behcet Uz Child Disease and Pediatric Surgery Training and Research Hospital, Izmir, Turkey
| | - Pelin Teke Kisa
- Division of Pediatric Metabolism and Nutrition, Department of Pediatrics, University of Health Sciences Dr. Behcet Uz Child Disease and Pediatric Surgery Training and Research Hospital, Izmir, Turkey
| |
Collapse
|
3
|
Ngqaneka T, Khoza S, Magwebu ZE, Chauke CG. Mutational analysis of BFSP1, CRYBB1, GALK1, and GJA8 in captive-bred vervet monkeys (Chlorocebus aethiops). J Med Primatol 2020; 49:79-85. [PMID: 31975409 DOI: 10.1111/jmp.12455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 11/08/2019] [Accepted: 12/06/2019] [Indexed: 11/28/2022]
Abstract
BACKGROUND Congenital cataract has been reported in a colony of captive-bred vervet monkeys (Chlorocebus aethiops). METHODS Molecular tools such as genotyping and gene expression were used to identify mutations associated with congenital cataract in this vervet colony. Beaded filament structural protein 1 (BFSP1), beta-crystallin B1 (CRYBB1), galactokinase1 (GALK1), and gap junction alpha-8 protein (GJA8) were screened, sequenced, and analyzed for mutations in 24 vervet monkeys (control and cataract). RESULTS Five missense sequence variants were identified (V147E, A167P, L212F, N55K, and T247A), three of which were found to be potentially disease-causing. Furthermore, downregulation was observed in BFSP1, CRYBB1, and GALK1 genes. CONCLUSION This study reports two cases of incomplete penetrance and/or uniparental disomy (L212F and T247A) in BSFP1. Mutations in BSFP1 together with three mutations in GALK1 and GJA8 were predicted to be disease-causing.
Collapse
Affiliation(s)
- Thobile Ngqaneka
- Primate Unit and Delft Animal Centre (PUDAC), South African Medical Research Council, Tygerberg, South Africa
| | - Sanele Khoza
- Primate Unit and Delft Animal Centre (PUDAC), South African Medical Research Council, Tygerberg, South Africa
| | - Zandisiwe E Magwebu
- Primate Unit and Delft Animal Centre (PUDAC), South African Medical Research Council, Tygerberg, South Africa
| | - Chesa G Chauke
- Primate Unit and Delft Animal Centre (PUDAC), South African Medical Research Council, Tygerberg, South Africa
| |
Collapse
|
4
|
Mayer AK, Balousha G, Sharkia R, Mahajnah M, Ayesh S, Schulze M, Buchert R, Zobor D, Azem A, Schöls L, Bauer P, Wissinger B. Unraveling the genetic cause of hereditary ophthalmic disorders in Arab societies from Israel and the Palestinian Authority. Eur J Hum Genet 2020; 28:742-753. [PMID: 31896775 DOI: 10.1038/s41431-019-0566-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 11/12/2019] [Accepted: 12/10/2019] [Indexed: 11/09/2022] Open
Abstract
Visual impairment due to inherited ophthalmic disorders is amongst the most common disabilities observed in populations practicing consanguineous marriages. Here we investigated the molecular genetic basis of an unselected broad range of ophthalmic disorders in 20 consanguineous families from Arab villages of Israel and the Palestinian Authority. Most patients had little or very poor prior clinical workup and were recruited in a field study. Homozygosity mapping followed by candidate gene sequencing applying conventional Sanger sequencing or targeted next generation sequencing was performed in six families. In the remaining 14 families, one affected subject per family was chosen for whole exome sequencing. We discovered likely disease-causing variants, all homozygous, in 19 of 20 independent families (95%) including a previously reported novel disease gene for congenital nystagmus associated with foveal hypoplasia. Moreover, we found a family in which disease-causing variants for two collagenopathies - Stickler and Knobloch syndrome - segregate within a large sibship. Nine of the 19 distinct variants observed in this study were novel. Our study demonstrated a very high molecular diagnostic yield for a highly diverse spectrum of rare ophthalmic disorders in Arab patients from Israel and the Palestinian Authority, even with very limited prior clinical investigation. We conclude that 'genetic testing first' may be an economic way to direct clinical care and to support proper genetic counseling and risk assessment in these families.
Collapse
Affiliation(s)
- Anja K Mayer
- Institute for Ophthalmic Research, Molecular Genetics Laboratory, Tuebingen, Germany.,Praxis fuer Humangenetik Tuebingen, Tuebingen, Germany
| | - Ghassan Balousha
- Department of Pathology and Histology, Al-Quds University, Eastern Jerusalem, Palestinian Authority, Jerusalem, Israel
| | - Rajech Sharkia
- The Triangle Regional Research and Development Center, Kfar Qari', Israel.,Beit-Berl Academic College, Beit-Berl, Israel
| | - Muhammad Mahajnah
- Child Neurology and Development Center, Hillel-Yaffe Medical Center, Hadera, Israel.,The Ruth and Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Suhail Ayesh
- Molecular Genetic Laboratory, Al-Makassed Islamic Charitable Society Hospital, Jerusalem, Israel
| | - Martin Schulze
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany.,Praxis fuer Humangenetik Tuebingen, Tuebingen, Germany
| | - Rebecca Buchert
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Ditta Zobor
- University Eye Hospital, University of Tuebingen, Tuebingen, Germany
| | - Abdussalam Azem
- The School of Neurobiology, Biochemistry and Biophysics, George S. Wise faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ludger Schöls
- Hertie Institute for Brain Research, University of Tuebingen, Tuebingen, Germany.,German Center of Neurodegenerative Diseases (DZNE), Tuebingen, Germany
| | - Peter Bauer
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Bernd Wissinger
- Institute for Ophthalmic Research, Molecular Genetics Laboratory, Tuebingen, Germany.
| |
Collapse
|
5
|
Affiliation(s)
- David J. Timson
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| |
Collapse
|
6
|
Lykke Eriksen P, Sørensen M, Grønbæk H, Hamilton-Dutoit S, Vilstrup H, Thomsen KL. Non-alcoholic fatty liver disease causes dissociated changes in metabolic liver functions. Clin Res Hepatol Gastroenterol 2019; 43:551-560. [PMID: 30770336 DOI: 10.1016/j.clinre.2019.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/02/2019] [Accepted: 01/10/2019] [Indexed: 02/04/2023]
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a major health concern affecting 25% of the world's population. It is generally held that a fatty liver does not influence liver function, but quantitative measurements of metabolic liver functions have not been systematically performed. We aimed to study selected hepatocellular metabolic functions in patients with different stages of NAFLD. METHODS Twenty-five non-diabetic, biopsy-proven NAFLD patients [12 with simple steatosis; 13 with non-alcoholic steatohepatitis (NASH)] and ten healthy controls were included in a cross-sectional study. Hepatocyte cytosolic function was assessed by the galactose elimination capacity (GEC), mitochondrial-cytosolic metabolic capacity by the functional hepatic nitrogen clearance (FHNC), microsomal function by the aminopyrine breath test, and excretory liver function by indocyanine green (ICG) elimination. RESULTS GEC was 20% higher in NAFLD than in controls [3.15 mmol/min (2.9-3.41) vs. 2.62 (2.32-2.93); P = 0.02]. FHNC was 30% lower in NAFLD [23.3 L/h (18.7-28.9) vs. 33.1 (28.9-37.9); P = 0.04], more so in simple steatosis [19.1 L/h (13.9-26.2); P = 0.003] and non-significantly in NASH [27.9 L/h (20.6-37.8); P = 0.19]. Aminopyrine metabolism was 25% lower in simple steatosis [8.9% (7.0-10.7)] and 50% lower in NASH [6.0% (4.5-7.5)] than in controls [11.9% (9.3-12.8)] (P < 0.001). ICG elimination was intact. CONCLUSIONS The hepatocellular metabolic functions were altered in a manner that was dissociated both by different effects on different liver functions and by different effects of different stages of NAFLD. Thus, NAFLD has widespread consequences for metabolic liver function, even in simple steatosis.
Collapse
Affiliation(s)
- Peter Lykke Eriksen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark.
| | - Michael Sørensen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| | - Henning Grønbæk
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| | - Stephen Hamilton-Dutoit
- Institute of Pathology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| | - Hendrik Vilstrup
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| | - Karen Louise Thomsen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| |
Collapse
|
7
|
Eriksen PL, Thomsen KL, Larsen LP, Grønbaek H, Vilstrup H, Sørensen M. Non-alcoholic steatohepatitis, but not simple steatosis, disturbs the functional homogeneity of the liver - a human galactose positron emission tomography study. Aliment Pharmacol Ther 2019; 50:84-92. [PMID: 31099410 DOI: 10.1111/apt.15293] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/12/2019] [Accepted: 04/18/2019] [Indexed: 12/16/2022]
Abstract
BACKGROUND The disease severity of non-alcoholic fatty liver disease (NAFLD) and the distinction between simple steatosis and non-alcoholic steatohepatitis (NASH) are based on the pathohistological presence of steatosis, inflammation, ballooning and fibrosis. However, little is known about the relation between such structural changes and the function of the afflicted liver. AIMS To investigate in vivo effects of hepatic fat fraction, ballooning and fibrosis on regional and whole liver metabolic function assessed by galactose elimination in NASH and simple steatosis. METHODS Twenty-five biopsy-proven, nondiabetic patients with NAFLD (13 NASH with low-grade fibrosis, 12 simple steatosis with no fibrosis) underwent 2-[18 F]fluoro-2-deoxy-d-galactose positron emission tomography and magnetic resonance imaging-derived proton density fat fraction of the liver. Nine healthy persons were included as controls. RESULTS In the NASH patients, the standardised hepatic uptake of 2-[18 F]fluoro-2-deoxy-d-galactose was reduced to 13.5 (95% confidence interval, 12.1-14.9) as compared with both simple steatosis and controls (16.4 (15.6-17.1), P < 0.001). Thus, the NASH patients had reduced regional metabolic liver function. The liver fat fraction diluted the standardised uptake equally in NASH and simple steatosis but the fibrosis and ballooning of NASH were associated with a further decrease. Moreover, the NASH livers exhibited increased variation in their standardised uptake values (coefficient of variation 13.8% vs 11.6% in simple steatosis and 10.2% in controls, P = 0.02), reflecting an increased functional heterogeneity. CONCLUSIONS In NASH, the regional metabolic liver function was lower and more heterogeneous than in both simple steatosis and healthy controls. Thus, NASH disturbs the normal homogeneous metabolic function of the liver.
Collapse
Affiliation(s)
- Peter Lykke Eriksen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus N, Denmark
| | - Karen Louise Thomsen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus N, Denmark
| | - Lars Peter Larsen
- Department of Radiology, Aarhus University Hospital, Aarhus N, Denmark
| | - Henning Grønbaek
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus N, Denmark
| | - Hendrik Vilstrup
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus N, Denmark
| | - Michael Sørensen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus N, Denmark.,Department of Nuclear Medicine & PET-Centre, Aarhus University Hospital, Aarhus N, Denmark
| |
Collapse
|
8
|
Cho SY, Kim S, Chung SK. Bilateral Corneal Opacities with Galactokinase Deficiency and Spinal Muscular Atrophy. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2019. [DOI: 10.3341/jkos.2019.60.12.1318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Soon Young Cho
- Department of Ophthalmology, Dongguk University College of Medicine, Gyeongju, Korea
| | - Sangbum Kim
- Department of Ophthalmology, Dongguk University College of Medicine, Gyeongju, Korea
| | | |
Collapse
|
9
|
Wada Y, Kikuchi A, Arai-Ichinoi N, Sakamoto O, Takezawa Y, Iwasawa S, Niihori T, Nyuzuki H, Nakajima Y, Ogawa E, Ishige M, Hirai H, Sasai H, Fujiki R, Shirota M, Funayama R, Yamamoto M, Ito T, Ohara O, Nakayama K, Aoki Y, Koshiba S, Fukao T, Kure S. Biallelic GALM pathogenic variants cause a novel type of galactosemia. Genet Med 2018; 21:1286-1294. [PMID: 30451973 DOI: 10.1038/s41436-018-0340-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 10/04/2018] [Indexed: 12/30/2022] Open
Abstract
PURPOSE Galactosemia is caused by metabolic disturbances at various stages of galactose metabolism, including deficiencies in enzymes involved in the Leloir pathway (GALT, GALK1, and GALE). Nevertheless, the etiology of galactosemia has not been identified in a subset of patients. This study aimed to explore the causes of unexplained galactosemia. METHODS Trio-based exome sequencing and/or Sanger sequencing was performed in eight patients with unexplained congenital galactosemia. In vitro enzymatic assays and immunoblot assays were performed to confirm the pathogenicity of the variants. RESULTS The highest blood galactose levels observed in each patient were 17.3-41.9 mg/dl. Bilateral cataracts were observed in two patients. In all eight patients, we identified biallelic variants (p.Arg82*, p.Ile99Leufs*46, p.Gly142Arg, p.Arg267Gly, and p.Trp311*) in the GALM encoding galactose mutarotase, which catalyzes epimerization between β- and α-D-galactose in the first step of the Leloir pathway. GALM enzyme activities were undetectable in lymphoblastoid cell lines established from two patients. Immunoblot analysis showed the absence of the GALM protein in the patients' peripheral blood mononuclear cells. In vitro GALM expression and protein stability assays revealed altered stabilities of the variant GALM proteins. CONCLUSION Biallelic GALM pathogenic variants cause galactosemia, suggesting the existence of type IV galactosemia.
Collapse
Affiliation(s)
- Yoichi Wada
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Atsuo Kikuchi
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
| | | | - Osamu Sakamoto
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Yusuke Takezawa
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Shinya Iwasawa
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Tetsuya Niihori
- Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan
| | - Hiromi Nyuzuki
- Department of Pediatrics, Niigata University School of Medicine, Niigata, Japan
| | - Yoko Nakajima
- Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Japan
| | - Erika Ogawa
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Mika Ishige
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Hiroki Hirai
- Department of Pediatrics, Ehime Prefectural Central Hospital, Matsuyama, Japan
| | - Hideo Sasai
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Ryoji Fujiki
- Department of Technology Development, Kazusa DNA Research Institute, Kisarazu, Japan
| | - Matsuyuki Shirota
- Division of Interdisciplinary Medical Sciences, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ryo Funayama
- Division of Cell Proliferation, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Masayuki Yamamoto
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| | - Tetsuya Ito
- Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Japan
| | - Osamu Ohara
- Department of Technology Development, Kazusa DNA Research Institute, Kisarazu, Japan
| | - Keiko Nakayama
- Division of Cell Proliferation, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yoko Aoki
- Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan
| | - Seizo Koshiba
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| | - Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Shigeo Kure
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.,Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| |
Collapse
|
10
|
Reis LM, Semina EV. Genetic landscape of isolated pediatric cataracts: extreme heterogeneity and variable inheritance patterns within genes. Hum Genet 2018; 138:847-863. [PMID: 30187164 DOI: 10.1007/s00439-018-1932-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 08/29/2018] [Indexed: 12/12/2022]
Abstract
Pediatric cataract represents an important cause of pediatric visual impairment. While both genetic and environmental causes for pediatric cataract are known, a large proportion remains idiopathic. The purpose of this review is to discuss genes involved in isolated pediatric cataract, with a focus on variable inheritance patterns within genes. Mutations in over 52 genes are known to cause isolated pediatric cataract, with a major contribution from genes encoding for crystallins, transcription factors, membrane proteins, and cytoskeletal proteins. Interestingly, both dominant and recessive inheritance patterns have been reported for mutations in 13 different cataract genes. For some genes, dominant and recessive alleles represent distinct types of mutations, but for many, especially missense variants, there are no clear patterns to distinguish between dominant and recessive alleles. Further research into the functional effects of these mutations, as well as additional data on the frequency of the identified variants, is needed to clarify variant pathogenicity. Exome sequencing continues to be successful in identifying novel genes associated with congenital cataract but is hindered by the extreme genetic heterogeneity of this condition. The large number of idiopathic cases suggests that more genes and potentially novel mechanisms of gene disruption remain to be identified.
Collapse
Affiliation(s)
- Linda M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA. .,Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
| |
Collapse
|
11
|
Stroek K, Bouva MJ, Schielen PCJI, Vaz FM, Heijboer AC, de Jonge R, Boelen A, Bosch AM. Recommendations for newborn screening for galactokinase deficiency: A systematic review and evaluation of Dutch newborn screening data. Mol Genet Metab 2018; 124:50-56. [PMID: 29580649 DOI: 10.1016/j.ymgme.2018.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/19/2018] [Accepted: 03/19/2018] [Indexed: 12/01/2022]
Abstract
INTRODUCTION Galactokinase (GALK) deficiency causes cataract leading to severe developmental consequences unless treated early. Because of the easy prevention and rapid reversibility of cataract with treatment, the Dutch Health Council advised to include GALK deficiency in the Dutch newborn screening program. The aim of this study is to establish the optimal screening method and cut-off value (COV) for GALK deficiency screening by performing a systematic review of the literature of screening strategies and total galactose (TGAL) values and by evaluating TGAL values in the first week of life in a cohort of screened newborns in the Netherlands. METHODS Systematic literature search strategies in OVID MEDLINE and OVID EMBASE were developed and study selection, data collection and analyses were performed by two independent investigators. A range of TGAL values measured by the Quantase Neonatal Total Galactose screening assay in a cohort of Dutch newborns in 2007 was evaluated. RESULTS Eight publications were included in the systematic review. All four studies describing screening strategies used TGAL as the primary screening marker combined with galactose-1-phosphate uridyltransferase (GALT) measurement that is used for classical galactosemia screening. TGAL COVs of 2200 μmol/L, 1665 μmol/L and 1110 μmol/L blood resulted in positive predictive values (PPV) of 100%, 82% and 10% respectively. TGAL values measured in the newborn period were reported for 39 GALK deficiency patients with individual values ranging from 3963 to 8159 μmol/L blood and 2 group values with mean 8892 μmol/L blood (SD ± 5243) and 4856 μmol/L blood (SD ± 461). Dutch newborn screening data of 72,786 newborns from 2007 provided a median TGAL value of 110 μmol/L blood with a range of 30-2431 μmol/L blood. CONCLUSION Based on TGAL values measured in GALK deficiency patients reported in the literature and TGAL measurements in the Dutch cohort by newborn screening we suggest to perform the GALK screening with TGAL as a primary marker with a COV of 2500 μmol/L blood, combined with GALT enzyme activity measurement as used in the classical galactosemia screening, to ensure detection of GALK deficiency patients and minimize false positive referrals.
Collapse
Affiliation(s)
- Kevin Stroek
- Department of Clinical Chemistry, Laboratory of Endocrinology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Marelle J Bouva
- Reference Laboratory for Neonatal Screening, Centre for Health Protection, National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
| | - Peter C J I Schielen
- Reference Laboratory for Neonatal Screening, Centre for Health Protection, National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
| | - Frédéric M Vaz
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Annemieke C Heijboer
- Department of Clinical Chemistry, Laboratory of Endocrinology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Clinical Chemistry, Endocrine Laboratory, VU University Medical Center, Amsterdam, The Netherlands.
| | - Robert de Jonge
- Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands.
| | - Anita Boelen
- Department of Clinical Chemistry, Laboratory of Endocrinology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Annet M Bosch
- Department of Pediatrics, Division of Metabolic Disorders, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| |
Collapse
|
12
|
McAuley M, Mesa-Torres N, McFall A, Morris S, Huang M, Pey AL, Timson DJ. Improving the Activity and Stability of Human Galactokinase for Therapeutic and Biotechnological Applications. Chembiochem 2018; 19:1088-1095. [DOI: 10.1002/cbic.201800025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Indexed: 01/04/2023]
Affiliation(s)
- Margaret McAuley
- School of Biological Sciences; Queen's University; Belfast; Medical Biology Centre; Lisburn Road Belfast BT9 7BL UK
| | - Noel Mesa-Torres
- Department of Physical Chemistry; University of Granada; Av. Fuentenueva s/n 18071 Granada Spain
| | - Aisling McFall
- School of Biological Sciences; Queen's University; Belfast; Medical Biology Centre; Lisburn Road Belfast BT9 7BL UK
| | - Sarah Morris
- School of Biological Sciences; Queen's University; Belfast; Medical Biology Centre; Lisburn Road Belfast BT9 7BL UK
| | - Meilan Huang
- School of Chemistry and Chemical Engineering; Queen's University; Belfast; David Keir Building Stranmillis Road Belfast BT9 5AG UK
| | - Angel L. Pey
- Department of Physical Chemistry; University of Granada; Av. Fuentenueva s/n 18071 Granada Spain
| | - David J. Timson
- School of Biological Sciences; Queen's University; Belfast; Medical Biology Centre; Lisburn Road Belfast BT9 7BL UK
- School of Pharmacy and Biomolecular Sciences; University of Brighton; Huxley Building Lewes Road Brighton BN2 4GJ UK
| |
Collapse
|
13
|
Schuler D, Höll C, Grün N, Ulrich J, Dillner B, Klebl F, Ammon A, Voll LM, Kämper J. Galactose metabolism and toxicity in Ustilago maydis. Fungal Genet Biol 2018; 114:42-52. [PMID: 29580862 DOI: 10.1016/j.fgb.2018.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 03/07/2018] [Accepted: 03/22/2018] [Indexed: 10/17/2022]
Abstract
In most organisms, galactose is metabolized via the Leloir pathway, which is conserved from bacteria to mammals. Utilization of galactose requires a close interplay of the metabolic enzymes, as misregulation or malfunction of individual components can lead to the accumulation of toxic intermediate compounds. For the phytopathogenic basidiomycete Ustilago maydis, galactose is toxic for wildtype strains, i.e. leads to growth repression despite the presence of favorable carbon sources as sucrose. The galactose sensitivity can be relieved by two independent modifications: (1) by disruption of Hxt1, which we identify as the major transporter for galactose, and (2) by a point mutation in the gene encoding the galactokinase Gal1, the first enzyme of the Leloir pathway. The mutation in gal1(Y67F) leads to reduced enzymatic activity of Gal1 and thus may limit the formation of putatively toxic galactose-1-phosphate. However, systematic deletions and double deletions of different genes involved in galactose metabolism point to a minor role of galactose-1-phosphate in galactose toxicity. Our results show that molecular triggers for galactose toxicity in U. maydis differ from yeast and mammals.
Collapse
Affiliation(s)
- David Schuler
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, Fritz Haber Weg 4, 76131 Karlsruhe, Germany
| | - Christina Höll
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, Fritz Haber Weg 4, 76131 Karlsruhe, Germany
| | - Nathalie Grün
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, Fritz Haber Weg 4, 76131 Karlsruhe, Germany
| | - Jonas Ulrich
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, Fritz Haber Weg 4, 76131 Karlsruhe, Germany
| | - Bastian Dillner
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, Fritz Haber Weg 4, 76131 Karlsruhe, Germany
| | - Franz Klebl
- FAU Erlangen-Nuremberg, Department of Biology, Molecular Plant Physiology, Staudtstrasse 5, 91058 Erlangen, Germany
| | - Alexandra Ammon
- Philips-University of Marburg, Department of Biology, Plant Physiology and Photo Biology, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Lars M Voll
- Philips-University of Marburg, Department of Biology, Plant Physiology and Photo Biology, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Jörg Kämper
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, Fritz Haber Weg 4, 76131 Karlsruhe, Germany.
| |
Collapse
|
14
|
Zhu X, Zhang S, Chang R, Lu Y. New cataract markers: Mechanisms of disease. Clin Chim Acta 2017; 472:41-45. [PMID: 28705775 DOI: 10.1016/j.cca.2017.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 07/08/2017] [Accepted: 07/09/2017] [Indexed: 11/28/2022]
Abstract
Cataract is caused by nutritional, metabolic, environmental, and genetic factors, and is a significant cause of blindness and visual impairment. In recent years, extensive research into the human genome has revealed that numerous genetic mutations are associated with cataract. These mutations affect a variety of genes, including those encoding crystallin, membrane proteins, cytoskeletal proteins, transcription factors, and metabolism-related proteins. Elucidation of these mutations and the genetic and molecular mechanisms has helped clarify the etiology of cataract and may facilitate its early diagnosis and treatment. This review summarizes recent advances in our knowledge and potential clinical of genetic markers of cataract.
Collapse
Affiliation(s)
- Xiangjia Zhu
- Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Eye Institute, Eye and Ear, Nose, and Throat Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Key Laboratory of Myopia, Ministry of Health, Shanghai 200031, People's Republic of China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200031, People's Republic of China
| | - Shaohua Zhang
- Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Eye Institute, Eye and Ear, Nose, and Throat Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Key Laboratory of Myopia, Ministry of Health, Shanghai 200031, People's Republic of China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200031, People's Republic of China
| | - Ruiqi Chang
- Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Eye Institute, Eye and Ear, Nose, and Throat Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Key Laboratory of Myopia, Ministry of Health, Shanghai 200031, People's Republic of China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200031, People's Republic of China
| | - Yi Lu
- Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Eye Institute, Eye and Ear, Nose, and Throat Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Key Laboratory of Myopia, Ministry of Health, Shanghai 200031, People's Republic of China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200031, People's Republic of China.
| |
Collapse
|
15
|
Chen J, Wang Q, Cabrera PE, Zhong Z, Sun W, Jiao X, Chen Y, Govindarajan G, Naeem MA, Khan SN, Ali MH, Assir MZ, Rahman FU, Qazi ZA, Riazuddin S, Akram J, Riazuddin SA, Hejtmancik JF. Molecular Genetic Analysis of Pakistani Families With Autosomal Recessive Congenital Cataracts by Homozygosity Screening. Invest Ophthalmol Vis Sci 2017; 58:2207-2217. [PMID: 28418495 PMCID: PMC5397132 DOI: 10.1167/iovs.17-21469] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To identify the genetic origins of autosomal recessive congenital cataracts (arCC) in the Pakistani population. Methods Based on the hypothesis that most arCC patients in consanguineous families in the Punjab areas of Pakistan should be homozygous for causative mutations, affected individuals were screened for homozygosity of nearby highly informative microsatellite markers and then screened for pathogenic mutations by DNA sequencing. A total of 83 unmapped consanguineous families were screened for mutations in 33 known candidate genes. Results Patients in 32 arCC families were homozygous for markers near at least 1 of the 33 known CC genes. Sequencing the included genes revealed homozygous cosegregating sequence changes in 10 families, 2 of which had the same variation. These included five missense, one nonsense, two frame shift, and one splice site mutations, eight of which were novel, in EPHA2, FOXE3, FYCO1, TDRD7, MIP, GALK1, and CRYBA4. Conclusions The above results confirm the usefulness of homozygosity mapping for identifying genetic defects underlying autosomal recessive disorders in consanguineous families. In our ongoing study of arCC in Pakistan, including 83 arCC families that underwent homozygosity mapping, 3 mapped using genome-wide linkage analysis in unpublished data, and 30 previously reported families, mutations were detected in approximately 37.1% (43/116) of all families studied, suggesting that additional genes might be responsible in the remaining families. The most commonly mutated gene was FYCO1 (14%), followed by CRYBB3 (5.2%), GALK1 (3.5%), and EPHA2 (2.6%). This provides the first comprehensive description of the genetic architecture of arCC in the Pakistani population.
Collapse
Affiliation(s)
- Jianjun Chen
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 2Department of Ophthalmology, Shanghai Tenth People's Hospital, and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Qiwei Wang
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 3State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Patricia E Cabrera
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Zilin Zhong
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 2Department of Ophthalmology, Shanghai Tenth People's Hospital, and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Wenmin Sun
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 3State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Xiaodong Jiao
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Yabin Chen
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Gowthaman Govindarajan
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shaheen N Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | | | - Fawad Ur Rahman
- Layton Rahmatulla Benevolent Trust Hospital, Lahore, Pakistan
| | | | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan 5Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan 7National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan 7National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - S Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States 9McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| |
Collapse
|
16
|
Messina-Baas O, Cuevas-Covarrubias SA. Inherited Congenital Cataract: A Guide to Suspect the Genetic Etiology in the Cataract Genesis. Mol Syndromol 2017; 8:58-78. [PMID: 28611546 DOI: 10.1159/000455752] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2016] [Indexed: 01/23/2023] Open
Abstract
Cataracts are the principal cause of treatable blindness worldwide. Inherited congenital cataract (CC) shows all types of inheritance patterns in a syndromic and nonsyndromic form. There are more than 100 genes associated with cataract with a predominance of autosomal dominant inheritance. A cataract is defined as an opacity of the lens producing a variation of the refractive index of the lens. This variation derives from modifications in the lens structure resulting in light scattering, frequently a consequence of a significant concentration of high-molecular-weight protein aggregates. The aim of this review is to introduce a guide to identify the gene involved in inherited CC. Due to the manifold clinical and genetic heterogeneity, we discarded the cataract phenotype as a cardinal sign; a 4-group classification with the genes implicated in inherited CC is proposed. We consider that this classification will assist in identifying the probable gene involved in inherited CC.
Collapse
|
17
|
McAuley M, Huang M, Timson DJ. Insight into the mechanism of galactokinase: Role of a critical glutamate residue and helix/coil transitions. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1865:321-328. [PMID: 27789348 DOI: 10.1016/j.bbapap.2016.10.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 10/19/2016] [Accepted: 10/21/2016] [Indexed: 11/24/2022]
Abstract
Galactokinase, the enzyme which catalyses the first committed step in the Leloir pathway, has attracted interest due to its potential as a biocatalyst and as a possible drug target in the treatment of type I galactosemia. The mechanism of the enzyme is not fully elucidated. Molecular dynamics (MD) simulations of galactokinase with the active site residues Arg-37 and Asp-186 altered predicted that two regions (residues 174-179 and 231-240) had different dynamics as a consequence. Interestingly, the same two regions were also affected by alterations in Arg-105, Glu-174 and Arg-228. These three residues were identified as important in catalysis in previous computational studies on human galactokinase. Alteration of Arg-105 to methionine resulted in a modest reduction in activity with little change in stability. When Arg-228 was changed to methionine, the enzyme's interaction with both ATP and galactose was affected. This variant was significantly less stable than the wild-type protein. Changing Glu-174 to glutamine (but not to aspartate) resulted in no detectable activity and a less stable enzyme. Overall, these combined in silico and in vitro studies demonstrate the importance of a negative charge at position 174 and highlight the critical role of the dynamics in to key regions of the protein. We postulate that these regions may be critical for mediating the enzyme's structure and function.
Collapse
Affiliation(s)
- Margaret McAuley
- School of Biological Sciences, Queen's University Belfast, Medical Biology Building, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Meilan Huang
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, UK
| | - David J Timson
- School of Biological Sciences, Queen's University Belfast, Medical Biology Building, 97 Lisburn Road, Belfast BT9 7BL, UK; School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton BN2 4GJ, UK.
| |
Collapse
|
18
|
Timson DJ. The molecular basis of galactosemia — Past, present and future. Gene 2016; 589:133-41. [DOI: 10.1016/j.gene.2015.06.077] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/18/2015] [Accepted: 06/29/2015] [Indexed: 12/19/2022]
|
19
|
Abstract
Galactokinase catalyses the first committed step of the Leloir pathway, i.e. the ATP-dependent phosphorylation of α-D-galactose at C1-OH. Reduced galactokinase activity results in the inherited metabolic disease type II galactosaemia. However, inhibition of galactokinase is considered a viable approach to treating more severe forms of galactosaemia (types I and III). Considerable progress has been made in the identification of high affinity, selective inhibitors. Although the structure of galactokinase from a variety of species is known, its catalytic mechanism remains uncertain. Although the bulk of evidence suggests that the reaction proceeds via an active site base mechanism, some experimental and theoretical studies contradict this. The enzyme has potential as a biocatalyst in the production of sugar 1-phosphates. This potential is limited by its high specificity. A variety of approaches have been taken to identify galactokinase variants which are more promiscuous. These have broadened galactokinase's specificity to include a wide range of D- and L-sugars. Initial studies suggest that some of these alterations result in increased flexibility at the active site. It is suggested that modulation of protein flexibility is at least as important as structural modifications in determining the success or failure of enzyme engineering.
Collapse
|
20
|
Elzi DJ, Song M, Shiio Y. Role of galactose in cellular senescence. Exp Gerontol 2016; 73:1-4. [DOI: 10.1016/j.exger.2015.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/11/2015] [Accepted: 11/04/2015] [Indexed: 10/22/2022]
|
21
|
Eidem HR, McGary KL, Rokas A. Shared Selective Pressures on Fungal and Human Metabolic Pathways Lead to Divergent yet Analogous Genetic Responses. Mol Biol Evol 2015; 32:1449-55. [DOI: 10.1093/molbev/msv034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
|
22
|
Homozygosity mapping identifies a GALK1 mutation as the cause of autosomal recessive congenital cataracts in 4 adult siblings. Gene 2013; 534:218-21. [PMID: 24211322 DOI: 10.1016/j.gene.2013.10.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/14/2013] [Accepted: 10/25/2013] [Indexed: 11/21/2022]
Abstract
OBJECTIVE Monogenic congenital cataract is one of the most genetically heterogeneous ocular conditions with almost 30 different genes involved in its etiology. In adult patients, genotype-phenotype correlations are troubled by eye surgery during infancy and/or long-term ocular complications. Here, we describe the molecular diagnosis of GALK1 deficiency as the cause of autosomal recessive congenital cataract in a family from Costa Rica. METHODS Four affected siblings were included in the study. All of them underwent eye surgery during the first decade but medical records were not available. Congenital cataract was diagnosed by report. Molecular analysis included genome wide homozygosity mapping using a 250K SNP Affymetrix microarray followed by PCR amplification and direct nucleotide sequencing of candidate gene. RESULTS Genome wide homozygosity mapping revealed a 6Mb region of homozygosity shared by two affected siblings at 17q25. The GALK1 gene was included in this interval and direct sequencing of this gene revealed a homozygous c.1144C>T mutation (p.Q382) in all four affected subjects. CONCLUSIONS This work demonstrates the utility of homozygosity mapping in the retrospective diagnosis of a family with congenital cataracts in which ocular surgery at early age, the lack of medical records, and the presence of long term eye complications, impeded a clear clinical diagnosis during the initial phases of evaluation.
Collapse
|
23
|
Bayarchimeg M, Ismail D, Lam A, Burk D, Kirk J, Hogler W, Flanagan SE, Ellard S, Hussain K. Galactokinase deficiency in a patient with congenital hyperinsulinism. JIMD Rep 2013; 5:7-11. [PMID: 23430910 DOI: 10.1007/8904_2011_110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 09/14/2011] [Accepted: 10/25/2011] [Indexed: 10/14/2022] Open
Abstract
BACKGROUND Galactokinase catalyses the first committed step in galactose metabolism, the conversion of galactose to galactose-1-phosphate. Galactokinase deficiency is an extremely rare form of galactosaemia, and the most frequent complication reported is cataracts. Congenital hyperinsulinism (CHI) is a cause of severe hypoglycaemia in the newborn period. Galactosaemia has not previously been reported in a neonate with concomitant CHI. AIMS To report the first case of a patient with CHI and galactokinase deficiency, and to describe the diagnostic pitfalls with bedside blood glucose testing in a neonate with combined galactokinase deficiency and CHI. PATIENTS/METHODS A 3-day-old baby girl from consanguineous parents presented with poor feeding, irritability and seizures. Capillary blood glucose testing using bedside test strips and glucometer showed a glucose level of 18 mmol/L, but the actual laboratory blood glucose level was only 1.8 mmol/L. After discontinuation of oral feeding (stopping provision of dietary galactose), the bedside capillary blood glucose correlated with laboratory glucose concentrations. RESULTS Biochemically the patient had CHI (blood glucose level 2.3 mmol/L with simultaneous serum insulin level of 30 mU/L) and galactokinase deficiency (elevated serum galactose level 0.62 μmol/L). Homozygous loss of function mutations in ABCC8 and GALK1 were found, which explained the patient's CHI and galactokinase deficiency, respectively. CONCLUSION This is the first reported case of CHI and galactokinase deficiency occurring in the same patient. Severe hypoglycaemia in neonates with CHI may go undetected with bedside blood glucose meters in patients with galactokinase deficiency.
Collapse
Affiliation(s)
- Mashbat Bayarchimeg
- Department of Endocrinology, Great Ormond Street Hospital for Children NHS Trust, London, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Chan WH, Biswas S, Ashworth JL, Lloyd IC. Congenital and infantile cataract: aetiology and management. Eur J Pediatr 2012; 171:625-30. [PMID: 22383071 DOI: 10.1007/s00431-012-1700-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 02/09/2012] [Indexed: 11/30/2022]
Abstract
Congenital cataract is the commonest worldwide cause of lifelong visual loss in children. Although congenital cataracts have a diverse aetiology, in many children, a cause is not identified; however, autosomal dominant inheritance is commonly seen. Early diagnosis either on the post-natal ward or in the community is important because appropriate intervention can result in good levels of visual function. However, visual outcome is largely dependent on the timing of surgery when dense cataracts are present. Good outcomes have been reported in children undergoing surgery before 6 weeks of age in children with unilateral cataract and before 10 weeks of age in bilateral cases. Placement of an artificial intraocular lens implant after removal of the cataract has become established practice in children over 2 years of age. There remains debate over the safety and predictability of intraocular lens implantation in infants. Despite early surgery and aggressive optical rehabilitation, children may still develop deprivation amblyopia, nystagmus, strabismus, and glaucoma. The diagnosis and management of congenital cataracts has improved substantially over the past 30 years with a concurrent improvement in outcomes for affected children. Many aspects of the pre-, intra-, and postoperative management of these patients continue to be refined, highlighting the need for good quality data and prospective collaborative studies in this field.
Collapse
Affiliation(s)
- Wai H Chan
- Manchester Academic Health Science Centre, Manchester Royal Eye Hospital, Central Manchester Foundation Trust, The University of Manchester, Oxford Road, Manchester, M13 9WH, UK
| | | | | | | |
Collapse
|
25
|
Janzen N, Illsinger S, Meyer U, Shin YS, Sander J, Lücke T, Das AM. Early cataract formation due to galactokinase deficiency: impact of newborn screening. Arch Med Res 2011; 42:608-12. [PMID: 22154682 DOI: 10.1016/j.arcmed.2011.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 11/04/2011] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND AIMS Galactokinase (GALK) deficiency is an autosomal recessive disorder causing cataract formation that can be prevented or mitigated by early diagnosis and galactose-restricted diet. The aim of this retrospective study was to explore whether GALK-deficiency meets the criteria for neonatal mass screening programs. METHODS From 2000 until 2010, the Screening Laboratory Hannover performed newborn screening in 1,950,927 infants from Germany for galactosemia by measuring galactose-1-phosphate-uridyl-transferase and total galactose concentration (free galactose plus galactose-1-phosphate), including automatic screening for GALK deficiency. RESULTS Eleven cases were found with elevated galactose levels accompanied by normal transferase activity. Nine of 11 cases were informative; the diagnosis was established by demonstrating deficient activity of the GALK enzyme in erythrocytes. To our knowledge, screening did not produce any false negative results. All patients were treated with a galactose-restricted diet from the neonatal period or infancy. Three of nine patients suffered from congenital cataracts or eventual development of cataracts, despite normal galactose concentrations in blood. CONCLUSIONS Newborn screening for GALK deficiency prevents or at least mitigates cataract formation. As screening for GALK deficiency is technically simple, it seems to be reasonable to include this disorder in routine screening programs by simultaneous determination of transferase activity and quantification of galactose plus galactose-1-phosphate in dried blood spots.
Collapse
Affiliation(s)
- Nils Janzen
- Clinic for Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany.
| | | | | | | | | | | | | |
Collapse
|
26
|
N-acetylgalactosamine Kinase: A Naturally Promiscuous Small Molecule Kinase. Appl Biochem Biotechnol 2011; 166:57-63. [DOI: 10.1007/s12010-011-9403-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 09/26/2011] [Indexed: 10/17/2022]
|
27
|
Yi J, Yun J, Li ZK, Xu CT, Pan BR. Epidemiology and molecular genetics of congenital cataracts. Int J Ophthalmol 2011; 4:422-32. [PMID: 22553694 DOI: 10.3980/j.issn.2222-3959.2011.04.20] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Accepted: 07/10/2011] [Indexed: 11/02/2022] Open
Abstract
Congenital cataract is a crystallin severe blinding disease and genetic factors in disease development are important. Crystallin growth is under a combination of genes and their products in time and space to complete the coordination role of the guidance. Congenital cataract-related genes, included crystallin protein gene (CRYAA, CRYAB, CRYBA1/A3, CRYBA4, CRYBB1, CRYBB2, CRYBB3, CRYGC, CRYGD, CRYGS), gap junction channel protein gene (GJA1, GJA3, GJA8), membrane protein gene (GJA3, GJA8, MIP, LIM2), cytoskeletal protein gene (BF-SP2), transcription factor genes (HSF4, MAF, PITX3, PAX6), ferritin light chain gene (FTL), fibroblast growth factor (FGF) and so on. Currently, there are about 39 genetic loci isolated to which primary cataracts have been mapped, although the number is constantly increasing and depends to some extent on definition. We summarized the recent advances on epidemiology and genetic locations of congenital cataract in this review.
Collapse
Affiliation(s)
- Jun Yi
- Department of Vascular Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, Shaanxi Province, China
| | | | | | | | | |
Collapse
|
28
|
Hennermann JB, Schadewaldt P, Vetter B, Shin YS, Mönch E, Klein J. Features and outcome of galactokinase deficiency in children diagnosed by newborn screening. J Inherit Metab Dis 2011; 34:399-407. [PMID: 21290184 DOI: 10.1007/s10545-010-9270-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 12/13/2010] [Accepted: 12/23/2010] [Indexed: 10/18/2022]
Abstract
Galactokinase deficiency (GALK-D), an autosomal recessive disorder in the Leloir pathway, results in accumulation of galactose, galactitol, and galactonate and leads to early onset of juvenile bilateral cataract. Highest incidence of GALK-D is found in Romani populations. The migration wave due to the Yugoslavian civil war has changed the spectrum of inborn errors of metabolism within Europe. Hence, newborn screening (NBS) in the Berlin region, performed from 1991 until 2010 in 683,675 neonates, revealed an increased incidence of GALK-D of 1:40,000, comparable to that of galactose-1-phosphate-uridyltransferase deficiency. A total of 44% of GALK-D patients were of Romani origin. All patients of Bosnian or Serbian origin were homozygous for the Romani founder mutation p.P28T. Detection of GALK-D by NBS and early start of galactose-restricted diet resulted in regression or prevention of cataracts. Slight cataracts without visual impairment occurred in 50% of the patients, 56% of whom were noncompliant. Further clinical symptoms, e.g., hypoglycemia, mental retardation, microcephaly, and failure to thrive, were associated with noncompliance. With treatment, galactose in blood decreased from 8,892 ± 5,243 to 36.5 ± 49.3 μmol/l, galactose in urine from 31,820 ± 32,103 to 30.0 ± 36.1 μmol/mmol creatinine, galactitol in RBC from 1,584 ± 584 to 12.3 ± 9.4 μmol/l, and galactitol in urine from 11,724 ± 4,496 to 236 ± 116 μmol/mmol creatinine. This is the first presentation of outcome and clinical features in GALK-D patients diagnosed by NBS. As our data suggest, GALK-D should be considered for inclusion in NBS in populations expected to have substantial numbers of GALK-D carriers, e.g., Yugoslavian immigrants.
Collapse
Affiliation(s)
- Julia B Hennermann
- Department of Pediatrics, Charité Universitätsmedizin Berlin, Berlin, Germany.
| | | | | | | | | | | |
Collapse
|
29
|
The role of the active site residues in human galactokinase: implications for the mechanisms of GHMP kinases. Bioorg Chem 2011; 39:120-6. [PMID: 21474160 DOI: 10.1016/j.bioorg.2011.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 03/01/2011] [Accepted: 03/02/2011] [Indexed: 11/20/2022]
Abstract
Galactokinase catalyses the phosphorylation of galactose at the expense of ATP. Like other members of the GHMP family of kinases it is postulated to function through an active site base mechanism in which Asp-186 abstracts a proton from galactose. This asparate residue was altered to alanine and to asparagine by site-directed mutagenesis of the corresponding gene. This resulted in variant enzyme with no detectable galactokinase activity. Alteration of Arg-37, which lies adjacent to Asp-186 and is postulated to assist the catalytic base, to lysine resulted in an active enzyme. However, alteration of this residue to glutamate abolished activity. All the variant enzymes, except the arginine to lysine substitution, were structurally unstable (as judged by native gel electrophoresis in the presence of urea) compared to the wild type. This suggests that the lack of activity results from this structural instability, in addition to any direct effects on the catalytic mechanism. Computational estimations of the pK(a) values of the arginine and aspartate residues, suggest that Arg-37 remains protonated throughout the catalytic cycle whereas Asp-186 has an abnormally high pK(a) value (7.18). Quantum mechanics/molecular mechanics (QM/MM) calculations suggest that Asp-186 moves closer to the galactose molecule during catalysis. The experimental and theoretical studies presented here argue for a mechanism in which the C(1)-OH bond in the sugar is weakened by the presence of Asp-186 thus facilitating nucleophilic attack by the oxygen atom on the γ-phosphorus of ATP.
Collapse
|
30
|
Park HD, Kim YK, Park KU, Kim JQ, Song YH, Song J. A novel c.-22T>C mutation in GALK1 promoter is associated with elevated galactokinase phenotype. BMC MEDICAL GENETICS 2009; 10:29. [PMID: 19309526 PMCID: PMC2667498 DOI: 10.1186/1471-2350-10-29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 03/24/2009] [Indexed: 11/10/2022]
Abstract
Background Many genetic variations of GALK1 have been identified in the patients with galactokinase (GALK1) deficiency. However, the molecular characteristics of GALK1 in individuals with elevated GALK1 activity are relatively unknown. Methods We investigated the relationship between elevated GALK1 activity and the molecular GALK1 gene variations, and the molecular mechanism underlying elevated GALK1 activity. PCR products from 63 subjects, without any attenuation of galactose degradation enzymes, were sequenced to screen for nucleotide alterations in the GALK1 promoter. Results Three nucleotide substitutions were identified: c.-179A>G, c.-27A>C, and c.-22T>C. With respect to the c.-22T>C mutation, GALK1 activity in 13 subjects with the T/C or C/C genotype was significantly higher than those in 50 subjects with the T/T genotype (p < 0.001). The dual luciferase reporter assay in Hep3B cells showed that the luciferase activity with the GALK1 promoter with the c.-22C mutant allele increased approximately 2.5-fold, compared to that with the c.-22T. A specific DNA-protein complex was observed in an electrophoretic mobility shift assay, with slightly higher affinity to c.-22C than to c.-22T. Conclusion The c.-22T>C mutation, which was observed frequently in individuals with elevated GALK1 activity, increased the expression of a reporter gene through enhanced binding of a currently unidentified nuclear protein. These results suggest that the elevated GALK1 activity resulted from enhanced gene expression, due to nucleotide variation within GALK1 promoter.
Collapse
Affiliation(s)
- Hyung-Doo Park
- Ilsong Institute of Life Science, Hallym University, Anyang, Korea.
| | | | | | | | | | | |
Collapse
|
31
|
Park HD, Bang YL, Park KU, Kim JQ, Jeong BH, Kim YS, Song YH, Song J. Molecular and biochemical characterization of the GALK1 gene in Korean patients with galactokinase deficiency. Mol Genet Metab 2007; 91:234-8. [PMID: 17517531 DOI: 10.1016/j.ymgme.2007.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 04/06/2007] [Accepted: 04/06/2007] [Indexed: 11/26/2022]
Abstract
Galactokinase (GALK) deficiency is an autosomal recessive disorder characterized by elevation of blood galactose concentration and diminished galactose-1-phosphate, leading to the production of galactitol. To investigate the molecular defects of GALK1 gene and the biochemical characteristics of their mutant proteins, PCR-direct sequencing and in vitro expression analysis in Cos7 cells were performed in five Korean patients with GALK deficiency galactosemia. Four missense mutations (p.G137R, p.R256W, p.R277Q, and p.V281M) and one small insertion (c.850_851insG) were identified. Among four patients with severely reduced GALK activity, two were found to be homozygotes for p.R256W and the other two were compound heterozygotes for different molecular defects (p.G137R/p.R277Q and p.V281M/c.850_851insG). One Patient with moderately decreased GALK activity was heterozygous for p.R256W. Expression analysis in Cos7 cells confirmed that each of the mutations resulted in reduction of GALK activity and caused GALK deficiency.
Collapse
Affiliation(s)
- Hyung-Doo Park
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Sidjanin DJ, McElwee J, Miller B, Aguirre GD. Cloning of canine galactokinase (GALK1) and evaluation as a candidate gene for hereditary cataracts in Labrador retrievers. Anim Genet 2005; 36:265-6. [PMID: 15932415 PMCID: PMC1509098 DOI: 10.1111/j.1365-2052.2005.01275.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D J Sidjanin
- Department of Ophthalmology, The Eye Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
| | | | | | | |
Collapse
|
33
|
Abstract
Galactokinase plays a key role in normal galactose metabolism by catalyzing the conversion of alpha-d-galactose to galactose 1-phosphate. Within recent years, the three-dimensional structures of human galactokinase and two bacterial forms of the enzyme have been determined. Originally, the gene encoding galactokinase in humans was mapped to chromosome 17. An additional gene, encoding a protein with sequence similarity to galactokinase, was subsequently mapped to chromosome 15. Recent reports have shown that this second gene (GALK2) encodes an enzyme with greater activity against GalNAc than galactose. This enzyme, GalNAc kinase, has been implicated in a salvage pathway for the reutilization of free GalNAc derived from the degradation of complex carbohydrates. Here we report the first structural analysis of a GalNAc kinase. The structure of the human enzyme was solved in the presence of MnAMPPNP and GalNAc or MgATP and GalNAc (which resulted in bound products in the active site). The enzyme displays a distinctly bilobal appearance with its active site wedged between the two domains. The N-terminal region is dominated by a seven-stranded mixed beta-sheet, whereas the C-terminal motif contains two layers of anti-parallel beta-sheet. The overall topology displayed by GalNAc kinase places it into the GHMP superfamily of enzymes, which generally function as small molecule kinases. From this investigation, the geometry of the GalNAc kinase active site before and after catalysis has been revealed, and the determinants of substrate specificity have been defined on a molecular level.
Collapse
Affiliation(s)
- James B Thoden
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | |
Collapse
|
34
|
Thoden JB, Timson DJ, Reece RJ, Holden HM. Molecular structure of human galactokinase: implications for type II galactosemia. J Biol Chem 2004; 280:9662-70. [PMID: 15590630 DOI: 10.1074/jbc.m412916200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Galactokinase functions in the Leloir pathway for galactose metabolism by catalyzing the MgATP-dependent phosphorylation of the C-1 hydroxyl group of alpha-D-galactose. The enzyme is known to belong to the GHMP superfamily of small molecule kinases and has attracted significant research attention for well over 40 years. Approximately 20 mutations have now been identified in human galactokinase, which result in the diseased state referred to as Type II galactosemia. Here we report the three-dimensional architecture of human galactokinase with bound alpha-D-galactose and Mg-AMPPNP. The overall fold of the molecule can be described in terms of two domains with the active site wedged between them. The N-terminal domain is dominated by a six-stranded mixed beta-sheet whereas the C-terminal motif contains six alpha-helices and two layers of anti-parallel beta-sheet. Those residues specifically involved in sugar binding include Arg37, Glu43, His44, Asp46, Gly183, Asp186, and Tyr236. The C-1 hydroxyl group of alpha-D-galactose sits within 3.3 A of the gamma-phosphorus of the nucleotide and 3.4 A of the guanidinium group of Arg37. The carboxylate side chain of Asp186 lies within approximately 3.2 A of the C-2 hydroxyl group of alpha-D-galactose and the guanidinium group of Arg37. Both Arg37 and Asp186 are strictly conserved among both prokaryotic and eukaryotic galactokinases. In addition to providing molecular insight into the active site geometry of the enzyme, the model also provides a structural framework upon which to more fully understand the consequences of the those mutations known to give rise to Type II galactosemia.
Collapse
Affiliation(s)
- James B Thoden
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | | | | | |
Collapse
|
35
|
Reddy MA, Francis PJ, Berry V, Bhattacharya SS, Moore AT. Molecular genetic basis of inherited cataract and associated phenotypes. Surv Ophthalmol 2004; 49:300-15. [PMID: 15110667 DOI: 10.1016/j.survophthal.2004.02.013] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Congenital cataract is a leading cause of visual disability in children. Inherited isolated (non-syndromic) cataract represents a significant proportion of cases and recently many causative genetic mutations have been identified. Inherited cataract is known to be clinically and genetically heterogeneous. Eleven clear-cut cataract phenotypes have been described. Cataract may be inherited as autosomal dominant, autosomal recessive, or X-linked recessive traits, and 12 loci and 15 specific genes associated with inherited isolated cataract have been identified to date; it is likely that more genes remain to be discovered. The identification of remaining genes will not only improve our understanding of the mechanism of cataract formation but will shed new light on the developmental biology and biochemistry of the lens. Furthermore, it is possible that some of these genes will be implicated in the more common age related cataract, which also has a genetic component to its etiology.
Collapse
Affiliation(s)
- M Ashwin Reddy
- Institute of Ophthalmology, and Moorfields Eye Hospital, London, United Kingdom
| | | | | | | | | |
Collapse
|
36
|
Hartley A, Glynn SE, Barynin V, Baker PJ, Sedelnikova SE, Verhees C, de Geus D, van der Oost J, Timson DJ, Reece RJ, Rice DW. Substrate specificity and mechanism from the structure of Pyrococcus furiosus galactokinase. J Mol Biol 2004; 337:387-98. [PMID: 15003454 DOI: 10.1016/j.jmb.2004.01.043] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2003] [Revised: 01/16/2004] [Accepted: 01/24/2004] [Indexed: 11/29/2022]
Abstract
Galactokinase (GalK) catalyses the first step of the Leloir pathway of galactose metabolism, the ATP-dependent phosphorylation of galactose to galactose-1-phosphate. In man, defects in galactose metabolism can result in disorders with severe clinical consequences, and deficiencies in galactokinase have been linked with the development of cataracts within the first few months of life. The crystal structure of GalK from Pyrococcus furiosus in complex with MgADP and galactose has been determined to 2.9 A resolution to provide insights into the substrate specificity and catalytic mechanism of the enzyme. The structure consists of two domains with the active site in a cleft at the domain interface. Inspection of the substrate binding pocket identifies the amino acid residues involved in galactose and nucleotide binding and points to both structural and mechanistic similarities with other enzymes of the GHMP kinase superfamily to which GalK belongs. Comparison of the sequence of the Gal3p inducer protein, which is related to GalK and which forms part of the transcriptional activation of the GAL gene cluster in the yeast Saccharomyces cerevisiae, has led to an understanding of the molecular basis of galactose and nucleotide recognition. Finally, the structure has enabled us to further our understanding on the functional consequences of mutations in human GalK which cause galactosemia.
Collapse
Affiliation(s)
- Andrew Hartley
- Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Abstract
The four essential building blocks of cells are proteins, nucleic acids, lipids, and glycans. Also referred to as carbohydrates, glycans are composed of saccharides that are typically linked to lipids and proteins in the secretory pathway. Glycans are highly abundant and diverse biopolymers, yet their functions have remained relatively obscure. This is changing with the advent of genetic reagents and techniques that in the past decade have uncovered many essential roles of specific glycan linkages in living organisms. Glycans appear to modulate biological processes in the development and function of multiple physiologic systems, in part by regulating protein-protein and cell-cell interactions. Moreover, dysregulation of glycan synthesis represents the etiology for a growing number of human genetic diseases. The study of glycans, known as glycobiology, has entered an era of renaissance that coincides with the acquisition of complete genome sequences for multiple organisms and an increased focus upon how posttranslational modifications to protein contribute to the complexity of events mediating normal and disease physiology. Glycan production and modification comprise an estimated 1% of genes in the mammalian genome. Many of these genes encode enzymes termed glycosyltransferases and glycosidases that reside in the Golgi apparatus where they play the major role in constructing the glycan repertoire that is found at the cell surface and among extracellular compartments. We present a review of the recently established functions of glycan structures in the context of mammalian genetic studies focused upon the mouse and human species. Nothing tends so much to the advancement of knowledge as the application of a new instrument. The native intellectual powers of men in different times are not so much the causes of the different success of their labours, as the peculiar nature of the means and artificial resources in their possession. T. Hager: Force of Nature (1)
Collapse
Affiliation(s)
- John B Lowe
- Department of Pathology and Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan 48109, USA.
| | | |
Collapse
|
38
|
Timson DJ, Reece RJ. Sugar recognition by human galactokinase. BMC BIOCHEMISTRY 2003; 4:16. [PMID: 14596685 PMCID: PMC280648 DOI: 10.1186/1471-2091-4-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2003] [Accepted: 11/04/2003] [Indexed: 11/10/2022]
Abstract
BACKGROUND Galactokinase catalyses the first committed step of galactose catabolism in which the sugar is phosphorylated at the expense of MgATP. Recent structural studies suggest that the enzyme makes several contacts with galactose--five side chain and two main chain hydrogen bonds. Furthermore, it has been suggested that inhibition of galactokinase may help sufferers of the genetic disease classical galactosemia which is caused by defects in another enzyme of the pathway galactose-1-phosphate uridyl transferase. Galactokinases from different sources have a range of substrate specificities and a diversity of kinetic mechanisms. Therefore only studies on the human enzyme are likely to be of value in the design of therapeutically useful inhibitors. RESULTS Using recombinant human galactokinase expressed in and purified from E. coli we have investigated the sugar specificity of the enzyme and the kinetic consequences of mutating residues in the sugar-binding site in order to improve our understanding of substrate recognition by this enzyme. D-galactose and 2-deoxy-D-galactose are substrates for the enzyme, but N-acetyl-D-galactosamine, L-arabinose, D-fucose and D-glucose are all not phosphorylated. Mutation of glutamate-43 (which forms a hydrogen bond to the hydroxyl group attached to carbon 6 of galactose) to alanine results in only minor changes in the kinetic parameters of the enzyme. Mutation of this residue to glycine causes a ten-fold drop in the turnover number. In contrast, mutation of histidine 44 to either alanine or isoleucine results in insoluble protein following expression in E. coli. Alteration of the residue that makes hydrogen bonds to the hydroxyl attached to carbons 3 and 4 (aspartate 46) results in an enzyme that although soluble is essentially inactive. CONCLUSIONS The enzyme is tolerant to small changes at position 2 of the sugar ring, but not at positions 4 and 6. The results from site directed mutagenesis could not have been predicted from the crystal structure alone and needed to be determined experimentally.
Collapse
Affiliation(s)
- David J Timson
- School of Biological Sciences, The University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT. United Kingdom
- Present address School of Biology and Biochemistry, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Richard J Reece
- School of Biological Sciences, The University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT. United Kingdom
| |
Collapse
|
39
|
Burdon KP, McKay JD, Sale MM, Russell-Eggitt IM, Mackey DA, Wirth MG, Elder JE, Nicoll A, Clarke MP, FitzGerald LM, Stankovich JM, Shaw MA, Sharma S, Gajovic S, Gruss P, Ross S, Thomas P, Voss AK, Thomas T, Gécz J, Craig JE. Mutations in a novel gene, NHS, cause the pleiotropic effects of Nance-Horan syndrome, including severe congenital cataract, dental anomalies, and mental retardation. Am J Hum Genet 2003; 73:1120-30. [PMID: 14564667 PMCID: PMC1180491 DOI: 10.1086/379381] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Accepted: 08/28/2003] [Indexed: 11/03/2022] Open
Abstract
Nance-Horan syndrome (NHS) is an X-linked disorder characterized by congenital cataracts, dental anomalies, dysmorphic features, and, in some cases, mental retardation. NHS has been mapped to a 1.3-Mb interval on Xp22.13. We have confirmed the same localization in the original, extended Australian family with NHS and have identified protein-truncating mutations in a novel gene, which we have called "NHS," in five families. The NHS gene encompasses approximately 650 kb of genomic DNA, coding for a 1,630-amino acid putative nuclear protein. NHS orthologs were found in other vertebrates, but no sequence similarity to known genes was identified. The murine developmental expression profile of the NHS gene was studied using in situ hybridization and a mouse line containing a lacZ reporter-gene insertion in the Nhs locus. We found a complex pattern of temporally and spatially regulated expression, which, together with the pleiotropic features of NHS, suggests that this gene has key functions in the regulation of eye, tooth, brain, and craniofacial development.
Collapse
Affiliation(s)
- Kathryn P. Burdon
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - James D. McKay
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Michèle M. Sale
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Isabelle M. Russell-Eggitt
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - David A. Mackey
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - M. Gabriela Wirth
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - James E. Elder
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Alan Nicoll
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Michael P. Clarke
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Liesel M. FitzGerald
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - James M. Stankovich
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Marie A. Shaw
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Shiwani Sharma
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Srecko Gajovic
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Peter Gruss
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Shelley Ross
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Paul Thomas
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Anne K. Voss
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Tim Thomas
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Jozef Gécz
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| | - Jamie E. Craig
- Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia; Center for Human Genomics and Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC; Great Ormond Street Hospital for Children, London; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Department of Ophthalmology, Royal Children’s Hospital, and Murdoch Children's Research Institute, Melbourne; Department of Ophthalmology, University of Zürich, Zürich; West Leederville, Australia; Department of Ophthalmology, University of Newcastle upon Tyne, Newcastle upon Tyne; Department of Cytogenetics and Molecular Genetics, Women’s and Children’s Hospital and Department of Pediatrics, The University of Adelaide, Adelaide; Department of Ophthalmology, Flinders University, Bedford Park, Australia; Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb; Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, Goettingen, Germany; and Development and Neurobiology, Walter and Eliza Hall Institute, Parkville, Australia
| |
Collapse
|
40
|
Abstract
Aldose 1-epimerase or mutarotase (EC 5.1.3.3) is a key enzyme of carbohydrate metabolism catalysing the interconversion of the alpha- and beta-anomers of hexose sugars such as glucose and galactose. We identified an open reading frame in the human genome (BC014916) which has high sequence similarity to previously identified bacterial aldose 1-epimerases. This sequence was cloned into a bacterial expression vector, and expressed and purified from this source. Enzyme assays show that the protein has aldose 1-epimerase activity and exhibits a preference for galactose over glucose. Site-directed mutagenesis confirmed the involvement of three residues involved in catalysis and substrate binding.
Collapse
Affiliation(s)
- David J Timson
- School of Biological Sciences, The University of Manchester, 2.205 Stopford Building, Oxford Road, M13 9PT, Manchester, UK
| | | |
Collapse
|
41
|
Goswami S, Sheets NL, Zavadil J, Chauhan BK, Bottinger EP, Reddy VN, Kantorow M, Cvekl A. Spectrum and range of oxidative stress responses of human lens epithelial cells to H2O2 insult. Invest Ophthalmol Vis Sci 2003; 44:2084-93. [PMID: 12714647 PMCID: PMC2080867 DOI: 10.1167/iovs.02-0882] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Oxidative stress (OS) is believed to be a major contributor to age-related cataract and other age-related diseases. METHODS cDNA microarrays were used to identify the spectrum and range of genes with transcript levels that are altered in response to acute H(2)O(2)-induced OS in human lens epithelial (HLE) cells. HLE cells were treated with 50 microM H(2)O(2) for 1 hour in the absence of serum, followed by a return to complete medium. RNAs were prepared from treated and untreated cells at 0, 1, 2, and 8 hours after H(2)O(2) treatment. RESULTS The data showed 1171 genes that were significantly up- and downregulated in response to H(2)O(2) treatment. Several functional subcategories of genes were identified, including those encoding DNA repair proteins, antioxidant defense enzymes, molecular chaperones, protein biosynthesis enzymes, and trafficking and degradation proteins. Differential expression of selected genes was confirmed at the level of RNA and/or protein. Many of the identified genes (e.g., glutathione S-transferase [MGST2], thioredoxin reductase beta, and peroxiredoxin 2) have been identified as participants in OS responses in the lens and other systems. Some genes induced by OS in the current study (e.g., oxygen regulated protein [ORP150] and heat shock protein [HSP40]) are better known to respond to other forms of stress. Two genes (receptor tyrosine kinase [AXL/ARK] and protein phosphatase 2A) are known to be differentially expressed in cataract. Most of the genes point to a novel pathways associated with OS. CONCLUSIONS The present data provide a global perspective on those genes that respond to acute OS, point to novel genes and pathways associated with OS, and set the groundwork for understanding the functions of OS-related genes in lens protection and disease.
Collapse
Affiliation(s)
- Sumanta Goswami
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Nancy L. Sheets
- Department of Biology, West Virginia University, Morgantown, West Virginia
| | - Jiři Zavadil
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, New York
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Bharesh K. Chauhan
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Erwin P. Bottinger
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, New York
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Venkat N. Reddy
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | - Marc Kantorow
- Department of Biology, West Virginia University, Morgantown, West Virginia
| | - Aleš Cvekl
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, New York
| |
Collapse
|
42
|
Timson DJ, Reece RJ. Functional analysis of disease-causing mutations in human galactokinase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:1767-74. [PMID: 12694189 DOI: 10.1046/j.1432-1033.2003.03538.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Galactokinase (EC 2.7.1.6) catalyzes the first committed step in the catabolism of galactose. The sugar is phosphorylated at position 1 at the expense of ATP. Lack of fully functional galactokinase is one cause of the inherited disease galactosemia, the main clinical manifestation of which is early onset cataracts. Human galactokinase (GALK1) was expressed in and purified from Escherichia coli. The recombinant enzyme was both soluble and active. Product inhibition studies showed that the most likely kinetic mechanism of the enzyme was an ordered ternary complex one in which ATP is the first substrate to bind. The lack of a solvent kinetic isotope effect suggests that proton transfer is unlikely to be involved in the rate determining step of catalysis. Ten mutations that are known to cause galactosemia were constructed and expressed in E. coli. Of these, five (P28T, V32M, G36R, T288M and A384P) were insoluble following induction and could not be studied further. Four of the remainder (H44Y, R68C, G346S and G349S) were all less active than the wild-type enzyme. One mutant (A198V) had kinetic properties that were essentially wild-type. These results are discussed both in terms of galactokinase structure-function relationships and how these functional changes may relate to the causes of galactosemia.
Collapse
Affiliation(s)
- David J Timson
- School of Biological Sciences, University of Manchester, United Kingdom
| | | |
Collapse
|
43
|
Chauhan BK, Reed NA, Yang Y, Cermák L, Reneker L, Duncan MK, Cvekl A. A comparative cDNA microarray analysis reveals a spectrum of genes regulated by Pax6 in mouse lens. Genes Cells 2002; 7:1267-83. [PMID: 12485166 PMCID: PMC2080869 DOI: 10.1046/j.1365-2443.2002.00602.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Pax6 is a transcription factor that is required for induction, growth, and maintenance of the lens; however, few direct target genes of Pax6 are known. RESULTS In this report, we describe the results of a cDNA microarray analysis of lens transcripts from transgenic mice over-expressing Pax6 in lens fibre cells in order to narrow the field of potential direct Pax6 target genes. This study revealed that the transcript levels were significantly altered for 508 of the 9700 genes analysed, including five genes encoding the cell adhesion molecules beta1-integrin, JAM1, L1 CAM, NCAM-140 and neogenin. Notably, comparisons between the genes differentially expressed in Pax6 heterozygous and Pax6 over-expressing lenses identified 13 common genes, including paralemmin, GDIbeta, ATF1, Hrp12 and Brg1. Immunohistochemistry and Western blotting demonstrated that Brg1 is expressed in the embryonic and neonatal (2-week-old) but not in 14-week adult lenses, and confirmed altered expression in transgenic lenses over-expressing Pax6. Furthermore, EMSA demonstrated that the BRG1 promoter contains Pax6 binding sites, further supporting the proposition that it is directly regulated by Pax6. CONCLUSIONS These results provide a list of genes with possible roles in lens biology and cataracts that are directly or indirectly regulated by Pax6.
Collapse
Affiliation(s)
- Bharesh K Chauhan
- The Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | | | | | | | | | | | |
Collapse
|
44
|
Bosch AM, Bakker HD, van Gennip AH, van Kempen JV, Wanders RJA, Wijburg FA. Clinical features of galactokinase deficiency: a review of the literature. J Inherit Metab Dis 2002; 25:629-34. [PMID: 12705493 DOI: 10.1023/a:1022875629436] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Galactokinase deficiency (McKusick 230200) is a rare autosomal recessive inborn error of galactose metabolism. Cataract and, rarely, pseudotumor cerebri caused by galactitol accumulation seem to be the only consistently reported abnormalities in this disorder. We performed a literature search to obtain information on the clinical spectrum of galactokinase deficiency. A total of 25 publications were traced describing 55 galactokinase-deficient patients. Cataract was reported in most patients. Clinical abnormalities other than cataract were reported in 15 (35%) out of 43 cases on which information was available. However, all symptoms were reported infrequently and a causal relationship with the galactokinase deficiency is unlikely. As cataract and pseudotumor cerebri appear to be the sole complications of galactokinase deficiency, the outcome for patients with galactokinase deficiency is much better than for patients with classical galactosaemia (McKusick 230400), a more common autosomal recessive disorder of galactose metabolism caused by galactose-1-phosphate uridyltransferase (GALT; EC 2.7.7.12) deficiency. Long-term follow-up of patients with this disorder has shown that, in spite of a severely galactose-restricted diet, most patients develop abnormalities such as a disturbed mental and/or motor development, dyspraxia and hypergonadotropic hypogonadism. Endogenous production of galactose has been considered an important aetiological factor. Although damage may well occur in utero, available evidence suggests that damage will continue after birth. Inhibition of galactokinase may then be a promising approach for controlling damage in GALT-deficient patients.
Collapse
Affiliation(s)
- A M Bosch
- Emma Children's Hospital, Amsterdam, The Netherlands
| | | | | | | | | | | |
Collapse
|
45
|
Hunter M, Heyer E, Austerlitz F, Angelicheva D, Nedkova V, Briones P, Gata A, de Pablo R, László A, Bosshard N, Gitzelmann R, Tordai A, Kalmar L, Szalai C, Balogh I, Lupu C, Corches A, Popa G, Perez-Lezaun A, Kalaydjieva LV. The P28T mutation in the GALK1 gene accounts for galactokinase deficiency in Roma (Gypsy) patients across Europe. Pediatr Res 2002; 51:602-6. [PMID: 11978884 DOI: 10.1203/00006450-200205000-00010] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Galactokinase deficiency is an inborn error of metabolism that, if untreated, results in the development of cataracts in the first weeks of life. The disorder is rare worldwide, but has a high incidence among the Roma (Gypsies). In 1999, we reported the founder Romani mutation, P28T, identified in affected families from Bulgaria. Subsequent studies have detected the same mutation in Romani patients from different European countries. The screening of 803 unrelated control individuals of Romani ethnicity from Bulgaria, Hungary, and Spain has shown an overall carrier rate of 1:47 and an expected incidence of affected births about 1:10,000. Using disease haplotype analysis, the age of the P28T mutation was estimated at 750 y, preceding the splits of the proto-Roma into the numerous populations resident in Europe today. The findings suggest that the mutation has spread with the early diaspora of the Roma throughout Europe. Superimposed on this old distribution pattern is the new migration wave of the last decade, with large numbers of Roma moving to Western Europe as a result of the economic changes in the East and the wars in former Yugoslavia. The changing demographic pattern of Romani minorities can be expected to lead to a homogenization of the incidence of "private" Romani disorders and founder mutations. The P28T mutation is thus likely to account for a high proportion of galactokinase deficiency cases across Europe. Mutation-based pilot newborn screening programs would provide current incidence figures and help to design long-term prevention of infantile cataracts due to galactokinase deficiency.
Collapse
Affiliation(s)
- Michael Hunter
- Centre for Human Genetics, Edith Cowan University, Perth, W.A., Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Reich S, Hennermann J, Vetter B, Neumann LM, Shin YS, Söling A, Mönch E, Kulozik AE. An unexpectedly high frequency of hypergalactosemia in an immigrant Bosnian population revealed by newborn screening. Pediatr Res 2002; 51:598-601. [PMID: 11978883 DOI: 10.1203/00006450-200205000-00009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In galactokinase (GALK) deficiency, galactose cannot be phosphorylated into galactose-1-phosphate, which leads to cataract formation. Neonatal screening for hypergalactosemia in Berlin has been performed by thin-layer chromatography since 1978, which detects classical galactosemia and GALK deficiency. Until 1991, GALK deficiency has not been identified in a total of approximately 260,000 samples. In contrast, from 1992 to 1999, nine patients were detected in a total of approximately 240,000 screened newborns. One Turkish patient was homozygous for two novel S142I/G148C GALK mutations in close proximity to the putative ATP-binding site of the enzyme. The other eight children were born to five families belonging to the Bosnian refugee population consisting of approximately 30,000 individuals who have arrived in Berlin since 1991. In two of these families, GALK deficiency was subsequently diagnosed in siblings who had cataract surgery at 4 and 5 y of age, respectively. In all these 10 Bosnian patients, a homozygous P28T mutation located near the active center of the enzyme was identified. We propose that neonatal screening of populations with a significant proportion of Bosnians and possibly other southeastern Europeans, e.g. Romani, should be particularly directed toward GALK deficiency, an inborn error of metabolism that is readily amenable to effective treatment.
Collapse
Affiliation(s)
- Susanne Reich
- Children's Hospital, Charité, Campus Virchow, Humboldt University, D-10247 Berlin, Germany
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Okano Y, Asada M, Fujimoto A, Ohtake A, Murayama K, Hsiao KJ, Choeh K, Yang Y, Cao Q, Reichardt JK, Niihira S, Imamura T, Yamano T. A genetic factor for age-related cataract: identification and characterization of a novel galactokinase variant, "Osaka," in Asians. Am J Hum Genet 2001; 68:1036-42. [PMID: 11231902 PMCID: PMC1275622 DOI: 10.1086/319512] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2000] [Accepted: 01/26/2001] [Indexed: 11/03/2022] Open
Abstract
Galactokinase (GALK) deficiency is an autosomal recessive disorder characterized by hypergalactosemia and cataract formation. Through mass screening of newborn infants, we identified a novel and prevalent GALK variant (designated here as the "Osaka" variant) associated with an A198V mutation in three infants with mild GALK deficiency. GALK activity and the amount of immunoreactive protein in the mutant were both 20% of normal construct in expression analysis. The K(m) values for galactose and ATP-Mg(2+) in erythrocytes with homozygous A198V were similar to those of the healthy adult control subjects. A population study for A198V revealed prevalences of 4.1% in Japanese and 2.8% in Koreans, lower incidence in Taiwanese and Chinese, no incidence in blacks and whites from the United States, and a significantly high frequency (7.8%; P < .023) in Japanese individuals with bilateral cataract. This variant probably originated in Japanese and Korean ancestors and is one of the genetic factors that causes cataract in elderly individuals.
Collapse
Affiliation(s)
- Y Okano
- Department of Pediatrics, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Novelli G, Reichardt JK. Molecular basis of disorders of human galactose metabolism: past, present, and future. Mol Genet Metab 2000; 71:62-5. [PMID: 11001796 DOI: 10.1006/mgme.2000.3073] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Molecular cloning and characterization of all three human galactose-metabolic genes have led to the identification of a number of mutations which result in three forms of galactosemia which are caused by kinase (GALK), transferase (GALT), or epimerase (GALE) deficiency. We review here recent developments in the molecular characterization of all three disorders of human galactose metabolism. Recent progress in the biochemical and/or structural analyses of the GALT and GALE proteins has complemented human mutational studies. Interestingly, genotype/phenotype correlations have been modest as in some other Mendelian disorders. We discuss possible reasons for this apparent paradox. Finally, we note the panethnic nature of galactosemia and suggest a hypothesis for it.
Collapse
Affiliation(s)
- G Novelli
- Dipartimento di Biopatologia e Diagnostica per Immagini, Università di Roma Tor Vergata, Rome, 00133, Italy
| | | |
Collapse
|
49
|
Tyfield L, Reichardt J, Fridovich-Keil J, Croke DT, Elsas LJ, Strobl W, Kozak L, Coskun T, Novelli G, Okano Y, Zekanowski C, Shin Y, Boleda MD. Classical galactosemia and mutations at the galactose-1-phosphate uridyl transferase (GALT) gene. Hum Mutat 2000; 13:417-30. [PMID: 10408771 DOI: 10.1002/(sici)1098-1004(1999)13:6<417::aid-humu1>3.0.co;2-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Classical galactosemia is caused by a deficiency in activity of the enzyme galactose-1-phosphate uridyl transferase (GALT), which, in turn, is caused by mutations at the GALT gene. The disorder exhibits considerable allelic heterogeneity and, at the end of 1998, more than 150 different base changes were recorded in 24 different populations and ethnic groups in 15 countries worldwide. The mutations most frequently cited are Q188R, K285N, S135L, and N314D. Q188R is the most common mutation in European populations or in those predominantly of European descent. Overall, it accounts for 60-70% of mutant chromosomes, but there are significant differences in its relative frequency in individual populations. Individuals homoallelic for Q188R tend to have a severe phenotype and this is in keeping with the virtually complete loss of enzyme activity observed in in vitro expression systems. Globally, K285N is rarer, but in many European populations it can be found on 25-40% of mutant chromosomes. It is invariably associated with a severe phenotype. S135L is found almost exclusively in African Americans. In vitro expression results are discrepant, but some individuals carrying S135L appear to exhibit GALT activity in some tissues. Duarte 1 (or Los Angeles) and Duarte 2 (or Duarte) variants carry the same amino acid substitution, N314D, even though D1 is associated with increased erythrocyte GALT activity and D2 with reduced activity. N314D is in linkage disequilibrium with other base changes that differ on the D1 and D2 alleles. N314D does not impair GALT activity in in vitro expression systems. However, there are differences in the abundance of GALT protein in lymphoblastoid cells lines from D2 and D1 individuals. It is unclear whether the specific molecular changes that distinguish the D1 and D2 alleles account for the different activities. The considerable genetic heterogeneity documented to date undoubtedly contributes to the phenotypic heterogeneity that is observed in galactosemia. The additional effects of nonallelic variation and other constitutional factors on phenotypic variability remain to be elucidated.
Collapse
Affiliation(s)
- L Tyfield
- The Lewis Laboratories, Southmead Hospital, Bristol, England, United Kingdom.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Kolosha V, Anoia E, de Cespedes C, Gitzelmann R, Shih L, Casco T, Saborio M, Trejos R, Buist N, Tedesco T, Skach W, Mitelmann O, Ledee D, Huang K, Stambolian D. Novel mutations in 13 probands with galactokinase deficiency. Hum Mutat 2000; 15:447-53. [PMID: 10790206 DOI: 10.1002/(sici)1098-1004(200005)15:5<447::aid-humu6>3.0.co;2-m] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Galactokinase is an essential enzyme in the metabolism of galactose. Patients with deficiencies in galactokinase exhibit early-onset cataracts. We examined the sequence of the human galactokinase gene (GK1) from 13 patients exhibiting galactokinase deficiency and identified 12 novel mutations. One of the mutations occurred in six of the 13 probands examined, and the remaining 11 were unique mutations. Expression of each of the mutant GK1 genes in Xenopus oocytes resulted in very low galactokinase activity levels. These results provide important information regarding the types of GK1 mutations that occur in the human population.
Collapse
Affiliation(s)
- V Kolosha
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|