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Kong Y, Yi H, Li F, Duan X, Yang L, Fan X, Wu G, Ma M, Zha X, He Y. A novel missense mutation in the CRYBA2 caused autosomal dominant presenile cataract in a Chinese family. Mol Genet Genomics 2023:10.1007/s00438-023-02052-y. [PMID: 37438446 DOI: 10.1007/s00438-023-02052-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 06/25/2023] [Indexed: 07/14/2023]
Abstract
Presenile cataract is a relatively rare type of cataract, but its genetic mechanisms are currently not well understood. The precise identification of these causative genes is crucial for effective genetic counseling for patients and their families. The aim of our study was to identify the causative gene associated with presenile cataract in a Chinese family. In February 2020, a four-generation pedigree of presenile cataract patients was recruited at the 2nd Affiliated Hospital of Kunming Medical University. One patient and her healthy husband from the family underwent whole exome sequencing. The variant was validated through sanger sequencing, and co-segregation analysis was conducted in all family members to assess its pathogenicity. Molecular dynamics simulation (MDS) was used to analyze the conformation of both the wild type and pathogenic mutant loci p.Y153H of CRYBA2. We identified presenile cataract in the pedigree, which follows an autosomal-dominant pattern of inheritance. The family includes five clinically affected patients who all developed presenile cataract between the ages from 24 to 30. We confirmed the pathogenicity of a heterozygous missense variant (NM_057093:c.457T >C) in CRYBA2 within this family. The affected amino acid demonstrates high conservation across species. Subsequent sanger sequencing confirmed co-segregation of the disease in all family members. MDS analysis revealed that the p.Y153H mutant disrupted hydrogen bond formation between Y153 and R193 within the two β-strands of the fourth Greek key domain, leading to destabilization of the βA2-crystallin. In conclusion, a novel causative mutation (NM_057093:c.457T>C) in CRYBA2 might contribute to autosomal dominant presenile cataract.
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Affiliation(s)
- Yanbo Kong
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Haoan Yi
- Department of Cell Biology and Medical Genetics, Faculty of Basic Medical Science, Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Fan Li
- Department of Pathology and Pathophysiology, School of Medicine, Yunnan University, Kunming, 650500, Yunnan, China
| | - Xiu Duan
- Department of Cell Biology and Medical Genetics, Faculty of Basic Medical Science, Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Lipu Yang
- Department of Cell Biology and Medical Genetics, Faculty of Basic Medical Science, Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Xinyu Fan
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Guojiu Wu
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Minjun Ma
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Xu Zha
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650500, Yunnan, China.
| | - Yongshu He
- Department of Cell Biology and Medical Genetics, Faculty of Basic Medical Science, Kunming Medical University, Kunming, 650500, Yunnan, China.
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Shiels A, Hejtmancik JF. Inherited cataracts: Genetic mechanisms and pathways new and old. Exp Eye Res 2021; 209:108662. [PMID: 34126080 PMCID: PMC8595562 DOI: 10.1016/j.exer.2021.108662] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/13/2021] [Accepted: 06/01/2021] [Indexed: 12/15/2022]
Abstract
Cataract(s) is the clinical equivalent of lens opacity and is caused by light scattering either by high molecular weight protein aggregates in lens cells or disruption of the lens microarchitecture itself. Genetic mutations underlying inherited cataract can provide insight into the biological processes and pathways critical for lens homeostasis and transparency, classically including the lens crystallins, connexins, membrane proteins or components, and intermediate filament proteins. More recently, cataract genes have been expanded to include newly identified biological processes such as chaperone or protein degradation components, transcription or growth factors, channels active in the lens circulation, and collagen and extracellular matrix components. Cataracts can be classified by age, and in general congenital cataracts are caused by severe mutations resulting in major damage to lens proteins, while age related cataracts are associated with variants that merely destabilize proteins thereby increasing susceptibility to environmental insults over time. Thus there might be separate pathways to opacity for congenital and age-related cataracts whereby congenital cataracts induce the unfolded protein response (UPR) and apoptosis to destroy the lens microarchitecture, while in age related cataract high molecular weight (HMW) aggregates formed by denatured crystallins bound by α-crystallin result in light scattering without severe damage to the lens microarchitecture.
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Affiliation(s)
- Alan Shiels
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, 63110, USA.
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892-1860, USA.
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Mustafa OM, Daoud YJ. Is Dietary Milk Intake Associated with Cataract Extraction History in Older Adults? An Analysis from the US Population. J Ophthalmol 2020; 2020:2562875. [PMID: 32148937 PMCID: PMC7053483 DOI: 10.1155/2020/2562875] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 01/15/2020] [Accepted: 01/18/2020] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Galactose accumulation in the lens tissue is known to be cataractogenic. Whether consistent dietary intake of lactose-which consists of glucose and galactose-predisposes to senile cataract remains unclear. This study was conducted to investigate the association between a number of dietary milk intake indicators and cataract extraction history in a representative sample of older adults from the US population. Methods and Materials. This is a cross-sectional, population-based study. Participants of the United States National Health and Nutrition Examination Survey 2001-2008 who were ≥50 years old and provided a complete history of their usual daily dietary intake were included. Exclusion criteria were special diets, extreme daily energy intake, and missing outcome (i.e., cataract extraction history). Indicators of milk intake used were early-life intake regularity, current daily milk/total dairy intake amounts, and estimated lifelong milk exposure. Odds ratios (OR) and 99% confidence intervals (99% CI) were calculated with fitting weights to better represent the population-based estimates. RESULTS Among the 5930 studied participants, early-life milk intake regularity was not associated with cataract extraction history in age/sex/ethnicity-adjusted and multivariable-adjusted models (p trend = 0.064 and 0.094, respectively). Current daily milk intake was associated with a slight reduction in the likelihood of cataract extraction in the age/sex/ethnicity-adjusted model (OR = 0.885 per cup equivalents, 99% CI = 0.795-0.986) and in the multivariable model (OR = 0.871 per cup equivalents, 99% CI = 0.746-0.993). However, no such association was observed between quartiles of current dietary milk intake and cataract extraction history (p trend = 0.064 and 0.094, respectively). Current daily milk intake was associated with a slight reduction in the likelihood of cataract extraction in the age/sex/ethnicity-adjusted model (OR = 0.885 per cup equivalents, 99% CI = 0.795-0.986) and in the multivariable model (OR = 0.871 per cup equivalents, 99% CI = 0.746-0.993). However, no such association was observed between quartiles of current dietary milk intake and cataract extraction history (p trend = 0.064 and 0.094, respectively). Current daily milk intake was associated with a slight reduction in the likelihood of cataract extraction in the age/sex/ethnicity-adjusted model (OR = 0.885 per cup equivalents, 99% CI = 0.795-0.986) and in the multivariable model (OR = 0.871 per cup equivalents, 99% CI = 0.746-0.993). However, no such association was observed between quartiles of current dietary milk intake and cataract extraction history (. CONCLUSION There appears to be no direct relationship between several indicators of dietary milk consumption and cataract extraction history in the general American population.
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Affiliation(s)
- Osama M. Mustafa
- Cornea, Cataract, and Refractive Surgery Division, The Johns Hopkins University Wilmer Eye Institute, Baltimore, MD 21287, USA
| | - Yassine J. Daoud
- Cornea, Cataract, and Refractive Surgery Division, The Johns Hopkins University Wilmer Eye Institute, Baltimore, MD 21287, USA
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Abstract
Cataract, the clinical correlate of opacity or light scattering in the eye lens, is usually caused by the presence of high-molecular-weight (HMW) protein aggregates or disruption of the lens microarchitecture. In general, genes involved in inherited cataracts reflect important processes and pathways in the lens including lens crystallins, connexins, growth factors, membrane proteins, intermediate filament proteins, and chaperones. Usually, mutations causing severe damage to proteins cause congenital cataracts, while milder variants increasing susceptibility to environmental insults are associated with age-related cataracts. These may have different pathogenic mechanisms: Congenital cataracts induce the unfolded protein response and apoptosis. By contrast, denatured crystallins in age-related cataracts are bound by α-crystallin and form light-scattering HMW aggregates. New therapeutic approaches to age-related cataracts use chemical chaperones to solubilize HMW aggregates, while attempts are being made to regenerate lenses using endogenous stem cells to treat congenital cataracts.
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Affiliation(s)
- Alan Shiels
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA;
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-1860, USA;
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Shiels A, Hejtmancik JF. Genetics of human cataract. Clin Genet 2013; 84:120-7. [PMID: 23647473 PMCID: PMC3991604 DOI: 10.1111/cge.12182] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/30/2013] [Accepted: 04/30/2013] [Indexed: 12/15/2022]
Abstract
The pathogenesis of inherited cataracts of all kinds recapitulates the developmental and cell biology of the lens. Just as each novel mutation provides additional information about the structural or functional biology of the affected gene, each newly identified gene provides insight into the developmental and cellular biology of the lens. The set of genes currently known to be associated with cataract is far from complete, especially for age-related cataract, and there is much additional information to be discovered through further genetic studies.
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Affiliation(s)
- A Shiels
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
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Karas-Kuzelicki N, Pfeifer V, Lukac-Bajalo J. Synergistic effect of high lactase activity genotype and galactose-1-phosphate uridyl transferase (GALT) mutations on idiopathic presenile cataract formation. Clin Biochem 2008; 41:869-74. [PMID: 18454942 DOI: 10.1016/j.clinbiochem.2008.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 02/05/2008] [Accepted: 04/03/2008] [Indexed: 10/22/2022]
Abstract
OBJECTIVES To evaluate the possible synergistic role of partial galactose metabolism defects, high lactase (LPH) genotype and lactose and galactose ingestion in presenile cataract formation. DESIGN AND METHODS 51 patients with idiopathic presenile cataracts and 172 healthy cataract-free subjects were genotyped to determine their galactose-1-phosphate uridyl transferase (GALT) and LPH status. Whole milk, skimmed milk and yoghurt consumption was recorded in 19 cataract patients and 172 controls by questionnaire. RESULTS GALT mutations and whole milk consumption increased the risk of cataract formation in high LPH genotype group, but not in lactose intolerant subjects. Logistic regression analysis showed the synergistic effect of GALT and LPH mutations on cataract formation. CONCLUSIONS High lactase activity genotypes and mutations in galactose-1-phosphate uridyl transferase have a synergistic effect on presenile cataract formation.
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Abstract
On the 65th anniversary of Gregg's observation "Congenital cataract following German measles in the mother", rubella has retired as the leading cause of congenital cataract, from 87% of Gregg's cohort to less than 3% over the last 25 years and almost zero now in Australia and other developed countries. However, people must keep vigilance in maintaining immunization rates and encourage immunization in developing countries. At least one-fifth of congenital cataract is familial. Understanding the genetics of familial cataract will lead to better treatment of congenital as well as age-related cataract.
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Affiliation(s)
- David A Mackey
- Eye Clinic, Royal Hobart Hospital, University of Tasmania, Hobart, Tasmania, Australia.
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Karas N, Gobec L, Pfeifer V, Mlinar B, Battelino T, Lukac-Bajalo J. Mutations in galactose-1-phosphate uridyltransferase gene in patients with idiopathic presenile cataract. J Inherit Metab Dis 2003; 26:699-704. [PMID: 14707519 DOI: 10.1023/b:boli.0000005660.88944.2f] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Impaired activity of the enzyme galactose-1-phosphate uridyltransferase (GALT) has been proposed as a risk factor for idiopathic presenile cataract. A study was undertaken to determine the prevalence of the three most common mutations in the GALT gene (Q188R, K285N and N314D, including its variant Duarte-2) in a group of Slovenian patients with idiopathic presenile cataract. GALT activity was determined in the erythrocytes of 30 cataract patients. DNA was isolated from their blood and analysed for Q188R, K285N and N314D mutations and IVS5-24G>A intronic variation by means of polymerase chain reaction and digestion with restriction enzymes. The average GALT activity of the cataract group was 19.5+/-4.9 U/g Hb, which is lower than the normal range (p = 0.034). Frequencies of Q188R, K285N, N314D and Duarte-2 alleles in the cataract group were 0.00%, 5.0%, 11.7% and 3.3%, respectively. Only the frequency of the K285N mutation was significantly higher in the patient group than in the control group (p = 0.0244). Our results support the reported association of decreased GALT activity with idiopathic presenile cataract. Molecular analysis indicates that, in the Slovenian population, this association is linked to the K285N mutation, which is neonatally benign in heterozygotes.
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Affiliation(s)
- N Karas
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
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Lukac-Bajalo J, Marc J, Mlinar B, Karas N, Krzisnik C, Battelino T. Frequencies of Q188R and N314D mutations and IVS5-24g>A intron variation in the galactose-1-phosphate uridyl transferase (GALT) gene in the Slovenian population. Clin Chem Lab Med 2002; 40:1109-13. [PMID: 12521227 DOI: 10.1515/cclm.2002.194] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Numerous mutations in the galactose-1-phosphate uridyl transferase (GALT) gene have been found to impair GALT activity to different extent, causing galactosemia. This disorder exhibits considerable allelic heterogeneity in different populations and ethnic groups. The Q188R mutation accounts for 60-70% of classical galactosemia alleles in the Caucasian population. Individuals homoallelic for Q188R have a severe phenotype with complete loss of enzyme activity. Another form of GALT deficiency is Duarte galactosemia with N314D mutation associated alleles (Duarte-2). Although heterozygotes for classical galactosemia are asymptomatic at birth and Duarte galactosemia appears to be quite benign, there are some indications that these disorders can increase the risk of developing certain diseases later in life. The aim of our study was to analyze a healthy Slovenian population for the frequencies of Q188R and N314D mutations, and for the Duarte-2 indicative intronic variation IVS5-24G>A. DNA samples from 174 healthy subjects were analyzed for all three mutations by polymerase chain reaction and digestion with restriction enzymes. Allele frequencies for Q188R and N314D mutations and IVS5-24G>A intron variation were found to be 0.29%, 8.0% and 5.7%, respectively. These results correlate well with those reported for most other healthy Caucasian populations.
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Affiliation(s)
- Jana Lukac-Bajalo
- Department of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia.
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Taylor D. The Doyne Lecture. Congenital cataract: the history, the nature and the practice. Eye (Lond) 1998; 12 ( Pt 1):9-36. [PMID: 9614513 DOI: 10.1038/eye.1998.5] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- D Taylor
- Department of Ophthalmology, Great Ormond Street Hospital for Children London, UK
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Elsevier JP, Fridovich-Keil JL. The Q188R mutation in human galactose-1-phosphate uridylyltransferase acts as a partial dominant negative. J Biol Chem 1996; 271:32002-7. [PMID: 8943248 DOI: 10.1074/jbc.271.50.32002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A longstanding goal in the fields of molecular genetics and biochemistry has been to explain how naturally occurring mutations associated with human metabolic disease impair activity of the enzymes involved. This goal is particularly complex for enzymes composed of multiple subunits, because single mutations may exert both intra- and intersubunit effects on holoenzyme structure and function. We have previously applied a yeast coexpression system for human galactose-1-phosphate uridylyltransferase, a dimeric enzyme associated with galactosemia, to investigate the impact of naturally occurring mutations on subunit association and holoenzyme function (). Here we describe the purification and characterization of two heterodimers, R333W/wild type (WT) and Q188R/WT, revealing that although the first exhibits approximately 50% wild-type activity, the second exhibits only approximately 15% wild-type activity. Neither heterodimer varied significantly from the wild type with regard to apparent Km for either substrate, although Q188R/WT but not R333W/WT heterodimers demonstrated significantly increased thermal sensitivity relative to the wild-type enzyme. These results demonstrate for the first time a partial dominant negative effect caused by a naturally occurring mutation in human galactose-1-phosphate uridylyltransferase.
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Affiliation(s)
- J P Elsevier
- Graduate Program in Biochemistry and Molecular Biology, Emory University, Atlanta, Georgia 30322, USA
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Beigi B, O'Keefe M, Bowell R, Naughten E, Badawi N, Lanigan B. Ophthalmic findings in classical galactosaemia--prospective study. Br J Ophthalmol 1993; 77:162-4. [PMID: 8457508 PMCID: PMC504462 DOI: 10.1136/bjo.77.3.162] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Thirty three children with classical galactosaemia diagnosed through newborn screening are considered. It is concluded that cataract formation has a direct relationship with poor dietary control. Erythrocyte galactose-1-phosphate (Gal-1-P) levels do not correspond to cataract formation unless many times higher than normal. The value of crystalline lens biomicroscopy is confirmed as a useful method for monitoring the dietary and biochemical control in classical galactosaemia.
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Affiliation(s)
- B Beigi
- Department of Paediatric Ophthalmology, Children's Hospital, Dublin, Ireland
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