1
|
Drackley A, Peter M, Rathbun P, Ing A, Prada CE, Yap KL. Homozygosity for disease-causing variants in AMT and GLDC in a patient with severe nonketotic hyperglycinemia. Am J Med Genet A 2024; 194:e63622. [PMID: 38572626 DOI: 10.1002/ajmg.a.63622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 03/07/2024] [Accepted: 03/25/2024] [Indexed: 04/05/2024]
Abstract
Nonketotic hyperglycinemia (NKH) is a relatively well-characterized inborn error of metabolism that results in a combination of lethargy, hypotonia, seizures, developmental arrest, and, in severe cases, death early in life. Three genes encoding components of the glycine cleavage enzyme system-GLDC, AMT, and GCSH-are independently associated with NKH. We report on a patient with severe NKH in whom the homozygous pathogenic variant in AMT (NM_000481.3):c.602_603del (p.Lys201Thrfs*75) and the homozygous likely pathogenic variant in GLDC(NM_000170.2):c.2852C>A (p.Ser951Tyr) were both identified. Our patient demonstrates a novel combination of two homozygous disease-causing variants impacting the glycine cleavage pathway at two different components, and elicits management- and genetic counseling-related challenges for the family.
Collapse
Affiliation(s)
- Andy Drackley
- Department of Pathology & Laboratory Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
- Division of Genetics, Genomics, and Metabolism, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
| | - Merlene Peter
- Division of Genetics, Genomics, and Metabolism, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
| | - Pamela Rathbun
- Department of Pathology & Laboratory Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Alexander Ing
- Department of Pathology & Laboratory Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
- Division of Genetics, Genomics, and Metabolism, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Carlos E Prada
- Division of Genetics, Genomics, and Metabolism, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Kai Lee Yap
- Department of Pathology & Laboratory Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| |
Collapse
|
2
|
Demetriou K, Nisbet J, Coman D, Ewing AD, Phillips L, Smith S, Lipke M, Inwood A, Spicer J, Atthow C, Wilgen U, Robertson T, McWhinney A, Swenson R, Espley B, Snowdon B, McGill JJ, Summers KM. Molecular genetic analysis of candidate genes for glutaric aciduria type II in a cohort of patients from Queensland, Australia. Mol Genet Metab 2024; 142:108516. [PMID: 38941880 DOI: 10.1016/j.ymgme.2024.108516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 06/11/2024] [Accepted: 06/14/2024] [Indexed: 06/30/2024]
Abstract
Glutaric aciduria type II (GAII) is a heterogeneous genetic disorder affecting mitochondrial fatty acid, amino acid and choline oxidation. Clinical manifestations vary across the lifespan and onset may occur at any time from the early neonatal period to advanced adulthood. Historically, some patients, in particular those with late onset disease, have experienced significant benefit from riboflavin supplementation. GAII has been considered an autosomal recessive condition caused by pathogenic variants in the gene encoding electron-transfer flavoprotein ubiquinone-oxidoreductase (ETFDH) or in the genes encoding electron-transfer flavoprotein subunits A and B (ETFA and ETFB respectively). Variants in genes involved in riboflavin metabolism have also been reported. However, in some patients, molecular analysis has failed to reveal diagnostic molecular results. In this study, we report the outcome of molecular analysis in 28 Australian patients across the lifespan, 10 paediatric and 18 adult, who had a diagnosis of glutaric aciduria type II based on both clinical and biochemical parameters. Whole genome sequencing was performed on 26 of the patients and two neonatal onset patients had targeted sequencing of candidate genes. The two patients who had targeted sequencing had biallelic pathogenic variants (in ETFA and ETFDH). None of the 26 patients whose whole genome was sequenced had biallelic variants in any of the primary candidate genes. Interestingly, nine of these patients (34.6%) had a monoallelic pathogenic or likely pathogenic variant in a single primary candidate gene and one patient (3.9%) had a monoallelic pathogenic or likely pathogenic variant in two separate genes within the same pathway. The frequencies of the damaging variants within ETFDH and FAD transporter gene SLC25A32 were significantly higher than expected when compared to the corresponding allele frequencies in the general population. The remaining 16 patients (61.5%) had no pathogenic or likely pathogenic variants in the candidate genes. Ten (56%) of the 18 adult patients were taking the selective serotonin reuptake inhibitor antidepressant sertraline, which has been shown to produce a GAII phenotype, and another two adults (11%) were taking a serotonin-norepinephrine reuptake inhibitor antidepressant, venlafaxine or duloxetine, which have a mechanism of action overlapping that of sertraline. Riboflavin deficiency can also mimic both the clinical and biochemical phenotype of GAII. Several patients on these antidepressants showed an initial response to riboflavin but then that response waned. These results suggest that the GAII phenotype can result from a complex interaction between monoallelic variants and the cellular environment. Whole genome or targeted gene panel analysis may not provide a clear molecular diagnosis.
Collapse
Affiliation(s)
- Kalliope Demetriou
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, South Brisbane, QLD 4101, Australia
| | - Janelle Nisbet
- Queensland Lifespan Metabolic Medicine Service, Mater Hospital Brisbane, South Brisbane, QLD 4101, Australia
| | - David Coman
- Queensland Lifespan Metabolic Medicine Service, Mater Hospital Brisbane, South Brisbane, QLD 4101, Australia; Wesley Medical Centre, Auchenflower, QLD 4066, Australia; University of Queensland, St Lucia, QLD 4072, Australia
| | - Adam D Ewing
- Mater Research Institute-University of Queensland, Translational Research Institute, 37 Kent St, Woolloongabba, QLD 4102, Australia
| | - Liza Phillips
- Queensland Lifespan Metabolic Medicine Service, Mater Hospital Brisbane, South Brisbane, QLD 4101, Australia
| | - Sally Smith
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, South Brisbane, QLD 4101, Australia; Queensland Lifespan Metabolic Medicine Service, Mater Hospital Brisbane, South Brisbane, QLD 4101, Australia
| | - Michelle Lipke
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, South Brisbane, QLD 4101, Australia; Queensland Lifespan Metabolic Medicine Service, Mater Hospital Brisbane, South Brisbane, QLD 4101, Australia
| | - Anita Inwood
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, South Brisbane, QLD 4101, Australia; Queensland Lifespan Metabolic Medicine Service, Mater Hospital Brisbane, South Brisbane, QLD 4101, Australia; University of Queensland, St Lucia, QLD 4072, Australia
| | - Janette Spicer
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, South Brisbane, QLD 4101, Australia
| | - Catherine Atthow
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, South Brisbane, QLD 4101, Australia
| | - Urs Wilgen
- University of Queensland, St Lucia, QLD 4072, Australia; Chemical Pathology, Pathology Queensland, Royal Brisbane and Women's Hospital, Herston, QLD 4029, Australia
| | - Thomas Robertson
- University of Queensland, St Lucia, QLD 4072, Australia; Anatomical Pathology, Pathology Queensland, Royal Brisbane and Women's Hospital, Herston, QLD 4029, Australia
| | - Avis McWhinney
- Chemical Pathology, Mater Pathology, Mater Hospital, Mater Hospital Brisbane, QLD 4101, Australia
| | - Rebecca Swenson
- Chemical Pathology, Pathology Queensland, Royal Brisbane and Women's Hospital, Herston, QLD 4029, Australia
| | - Brayden Espley
- Chemical Pathology, Pathology Queensland, Royal Brisbane and Women's Hospital, Herston, QLD 4029, Australia
| | - Brianna Snowdon
- Chemical Pathology, Pathology Queensland, Royal Brisbane and Women's Hospital, Herston, QLD 4029, Australia
| | - James J McGill
- Queensland Lifespan Metabolic Medicine Service, Queensland Children's Hospital, South Brisbane, QLD 4101, Australia; Queensland Lifespan Metabolic Medicine Service, Mater Hospital Brisbane, South Brisbane, QLD 4101, Australia; Chemical Pathology, Pathology Queensland, Royal Brisbane and Women's Hospital, Herston, QLD 4029, Australia; Chemical Pathology, Mater Pathology, Mater Hospital, Mater Hospital Brisbane, QLD 4101, Australia
| | - Kim M Summers
- Mater Research Institute-University of Queensland, Translational Research Institute, 37 Kent St, Woolloongabba, QLD 4102, Australia.
| |
Collapse
|
3
|
Wolfsdorf JI, Derks TGJ, Drachmann D, Shah P, Thornton PS, Weinstein DA. Idiopathic Pathological Ketotic Hypoglycemia: Finding the Needle in a Haystack. Horm Res Paediatr 2024:1-12. [PMID: 38513624 DOI: 10.1159/000538483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 03/17/2024] [Indexed: 03/23/2024] Open
Abstract
Sick children often have a decreased appetite and experience vomiting and diarrhea; however, hypoglycemia (plasma glucose concentration ≤50 mg/dL or 2.8 mmol/L) is rare. Ketotic hypoglycemia (KH) is the most common cause of hypoglycemia presenting to an Emergency Department in a previously healthy child between 6 months and 6 years of age. Ketosis and hypoglycemia are now well understood to be normal physiologic responses of young children to prolonged fasting.There is now substantial evidence that the term KH describes a variety of conditions including both the lower end of the normal distribution of fasting tolerance in young children as well as numerous rare disorders that impair fasting adaptation. Recent advances in molecular genetic testing have led to the discovery of these rare disorders. Idiopathic pathological KH is a diagnosis of exclusion that describes rare children who have abnormally limited fasting tolerance, experience recurrent episodes of KH, or develop symptoms of hypoglycemia despite elevated ketone levels, and in whom an explanation cannot be found despite extensive investigation. This review provides an approach to distinguishing between physiological KH and pathological KH and includes recommendations for management.
Collapse
Affiliation(s)
- Joseph I Wolfsdorf
- Division of Endocrinology, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Terry G J Derks
- Section of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Danielle Drachmann
- Ketotic Hypoglycemia International, Skanderborg, Denmark, Patient-Centered Research, Evidera, London, UK
| | - Pratik Shah
- Paediatric Endocrinology and Diabetes, The Royal London Children's Hospital, Barts Health NHS Trust and Honorary Senior Lecturer, Queen Mary University London, London, UK
| | - Paul S Thornton
- Division of Endocrinology and Diabetes and the Congenital Hyperinsulinism Center, Cook Children's Medical Center and Department of Pediatrics, Burnett School of Medicine, Texas Christian University, Fort Worth, Texas, USA
| | - David A Weinstein
- Department of Pediatrics, University of Connecticut Health Center, Farmington, Connecticut, USA
| |
Collapse
|
4
|
Hames A, Khan S, Gilliland C, Goldman L, Lo HW, Magda K, Keathley J. Carriers of autosomal recessive conditions: are they really 'unaffected?'. J Med Genet 2023; 61:1-7. [PMID: 37775265 DOI: 10.1136/jmg-2023-109563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/11/2023] [Indexed: 10/01/2023]
Abstract
Mendel's Law of Dominance suggests that recessive disease expression requires the inheritance of two mutated alleles as the dominant, wildtype allele suppresses disease presentation leading to the expression of physiological normal phenotypes. However, there is existing evidence that challenges this school of thought. Here, we summarise existing literature evaluating metabolic and health impacts among carriers of autosomal recessive conditions, focusing on phenylketonuria (PKU), classical homocystinuria, galactosemia and Usher syndrome as examples. Our findings suggest that carriers, often described as 'unaffected', may actually display attenuated symptoms for the recessive disease they are carrying. For instance, PKU is an inborn error of metabolism characterised by the build-up of plasma phenylalanine attributed to the deficiency of the phenylalanine hydroxylase (PAH) enzyme. While less severe, PKU carriers also exhibit this impaired enzymatic activity, leading to elevated plasma phenylalanine levels, especially after phenylalanine consumption. Related to these metabolic alterations in the PAH pathway, there is early evidence to suggest that PKU carriers may have compromised cognitive and mental health outcomes. Overall, research on the health and metabolic impacts of PKU carriers is sparse, with most studies conducted several decades ago. However, early evidence suggests that intermediate phenotypes among carriers of autosomal recessive conditions are plausible. The illustrated possible intermediate phenotypes observed among carriers necessitates future research to determine possible clinical implications among this population.
Collapse
Affiliation(s)
- Amber Hames
- Department of Family Relations and Applied Nutrition, University of Guelph, Guelph, Southwestern Ontario, Canada
| | - Sophia Khan
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Southwestern Ontario, Canada
| | - Clara Gilliland
- Department of Food Science, University of Guelph, Guelph, Southwestern Ontario, Canada
| | - Lucy Goldman
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Southwestern Ontario, Canada
| | - Hillary Wh Lo
- Department of Family Relations and Applied Nutrition, University of Guelph, Guelph, Southwestern Ontario, Canada
| | - Kevin Magda
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Southwestern Ontario, Canada
- Department of Biomedical Sciences, University of Guelph, Guelph, Southwestern Ontario, Canada
| | - Justine Keathley
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Southwestern Ontario, Canada
| |
Collapse
|
5
|
Mendelian inheritance revisited: dominance and recessiveness in medical genetics. Nat Rev Genet 2023:10.1038/s41576-023-00574-0. [PMID: 36806206 DOI: 10.1038/s41576-023-00574-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2022] [Indexed: 02/22/2023]
Abstract
Understanding the consequences of genotype for phenotype (which ranges from molecule-level effects to whole-organism traits) is at the core of genetic diagnostics in medicine. Many measures of the deleteriousness of individual alleles exist, but these have limitations for predicting the clinical consequences. Various mechanisms can protect the organism from the adverse effects of functional variants, especially when the variant is paired with a wild type allele. Understanding why some alleles are harmful in the heterozygous state - representing dominant inheritance - but others only with the biallelic presence of pathogenic variants - representing recessive inheritance - is particularly important when faced with the deluge of rare genetic alterations identified by high throughput DNA sequencing. Both awareness of the specific quantitative and/or qualitative effects of individual variants and the elucidation of allelic and non-allelic interactions are essential to optimize genetic diagnosis and counselling.
Collapse
|
6
|
Fogh S, Dipace G, Bie A, Veiga‐da‐Cunha M, Hansen J, Kjeldsen M, Mosegaard S, Ribes A, Gregersen N, Aagaard L, Van Schaftingen E, Olsen RKJ. Variants in the ethylmalonyl-CoA decarboxylase (ECHDC1) gene: a novel player in ethylmalonic aciduria? J Inherit Metab Dis 2021; 44:1215-1225. [PMID: 33973257 PMCID: PMC8518634 DOI: 10.1002/jimd.12394] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 05/03/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022]
Abstract
Ethylmalonic acid (EMA) is a major and potentially cytotoxic metabolite associated with short-chain acyl-CoA dehydrogenase (SCAD) deficiency, a condition whose status as a disease is uncertain. Unexplained high EMA is observed in some individuals with complex neurological symptoms, who carry the SCAD gene (ACADS) variants, c.625G>A and c.511C>T. The variants have a high allele frequency in the general population, but are significantly overrepresented in individuals with elevated EMA. This has led to the idea that these variants need to be associated with variants in other genes to cause hyperexcretion of ethylmalonic acid and possibly a diseased state. Ethylmalonyl-CoA decarboxylase (ECHDC1) has been described and characterized as an EMA metabolite repair enzyme, however, its clinical relevance has never been investigated. In this study, we sequenced the ECHDC1 gene (ECHDC1) in 82 individuals, who were reported with unexplained high EMA levels due to the presence of the common ACADS variants only. Three individuals with ACADS c.625G>A variants were found to be heterozygous for ECHDC1 loss-of-function variants. Knockdown experiments of ECHDC1, in healthy human cells with different ACADS c.625G>A genotypes, showed that ECHDC1 haploinsufficiency and homozygosity for the ACADS c.625G>A variant had a synergistic effect on cellular EMA excretion. This study reports the first cases of ECHDC1 gene defects in humans and suggests that ECHDC1 may be involved in elevated EMA excretion in only a small group of individuals with the common ACADS variants. However, a direct link between ECHDC1/ACADS deficiency, EMA and disease could not be proven.
Collapse
Affiliation(s)
- Sarah Fogh
- Research Unit for Molecular Medicine, Department for Clinical MedicineAarhus University and Aarhus University HospitalAarhusDenmark
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | - Graziana Dipace
- Research Unit for Molecular Medicine, Department for Clinical MedicineAarhus University and Aarhus University HospitalAarhusDenmark
| | - Anne Bie
- Research Unit for Molecular Medicine, Department for Clinical MedicineAarhus University and Aarhus University HospitalAarhusDenmark
| | | | - Jakob Hansen
- Department of Forensic MedicineAarhus University HospitalAarhusDenmark
| | - Margrethe Kjeldsen
- Research Unit for Molecular Medicine, Department for Clinical MedicineAarhus University and Aarhus University HospitalAarhusDenmark
| | - Signe Mosegaard
- Research Unit for Molecular Medicine, Department for Clinical MedicineAarhus University and Aarhus University HospitalAarhusDenmark
| | - Antonia Ribes
- Secció d'Errors Congènits del Metabolisme‐IBC, Servei de Bioquímica i Genètica MolecularHospital Clínic, IDIBAPS, CIBERERBarcelonaSpain
| | - Niels Gregersen
- Research Unit for Molecular Medicine, Department for Clinical MedicineAarhus University and Aarhus University HospitalAarhusDenmark
| | - Lars Aagaard
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | | | - Rikke K. J. Olsen
- Research Unit for Molecular Medicine, Department for Clinical MedicineAarhus University and Aarhus University HospitalAarhusDenmark
| |
Collapse
|
7
|
Sklirou E, Alodaib AN, Dobrowolski SF, Mohsen AWA, Vockley J. Physiological Perspectives on the Use of Triheptanoin as Anaplerotic Therapy for Long Chain Fatty Acid Oxidation Disorders. Front Genet 2021; 11:598760. [PMID: 33584796 PMCID: PMC7875087 DOI: 10.3389/fgene.2020.598760] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 11/27/2020] [Indexed: 12/15/2022] Open
Abstract
Inborn errors of mitochondrial fatty acid oxidation (FAO) comprise the most common group of disorders identified through expanded newborn screening mandated in all 50 states in the United States, affecting 1:10,000 newborns. While some of the morbidity in FAO disorders (FAODs) can be reduced if identified through screening, a significant gap remains between the ability to diagnose these disorders and the ability to treat them. At least 25 enzymes and specific transport proteins are responsible for carrying out the steps of mitochondrial fatty acid metabolism, with at least 22 associated genetic disorders. Common symptoms in long chain FAODs (LC-FAODs) in the first week of life include cardiac arrhythmias, hypoglycemia, and sudden death. Symptoms later in infancy and early childhood may relate to the liver or cardiac or skeletal muscle dysfunction, and include fasting or stress-related hypoketotic hypoglycemia or Reye-like syndrome, conduction abnormalities, arrhythmias, dilated or hypertrophic cardiomyopathy, and muscle weakness or fasting- and exercise-induced rhabdomyolysis. In adolescent or adult-onset disease, muscular symptoms, including rhabdomyolysis, and cardiomyopathy predominate. Unfortunately, progress in developing better therapeutic strategies has been slow and incremental. Supplementation with medium chain triglyceride (MCT; most often a mixture of C8–12 fatty acids containing triglycerides) oil provides a fat source that can be utilized by patients with long chain defects, but does not eliminate symptoms. Three mitochondrial metabolic pathways are required for efficient energy production in eukaryotic cells: oxidative phosphorylation (OXPHOS), FAO, and the tricarboxylic (TCA) cycle, also called the Krebs cycle. Cell and mouse studies have identified a deficiency in TCA cycle intermediates in LC-FAODs, thought to be due to a depletion of odd chain carbon compounds in patients treated with a predominantly MCT fat source. Triheptanoin (triheptanoyl glycerol; UX007, Ultragenyx Pharmaceuticals) is chemically composed of three heptanoate (seven carbon fatty acid) molecules linked to glycerol through ester bonds that has the potential to replete TCA cycle intermediates through production of both acetyl-CoA and propionyl-CoA through medium chain FAO. Compassionate use, retrospective, and recently completed prospective studies demonstrate significant reduction of hypoglycemic events and improved cardiac function in LC-FAOD patients, but a less dramatic effect on muscle symptoms.
Collapse
Affiliation(s)
- Evgenia Sklirou
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Ahmad N Alodaib
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Newborn Screening and Biochemical Genetics Lab, Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Steven F Dobrowolski
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Al-Walid A Mohsen
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, United States
| | - Jerry Vockley
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Rare Disease Therapy, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, United States
| |
Collapse
|
8
|
Makris G, Lauber M, Rüfenacht V, Gemperle C, Diez-Fernandez C, Caldovic L, Froese DS, Häberle J. Clinical and structural insights into potential dominant negative triggers of proximal urea cycle disorders. Biochimie 2020; 183:89-99. [PMID: 33309754 DOI: 10.1016/j.biochi.2020.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 12/04/2020] [Accepted: 12/08/2020] [Indexed: 12/31/2022]
Abstract
Despite biochemical and genetic testing being the golden standards for identification of proximal urea cycle disorders (UCDs), genotype-phenotype correlations are often unclear. Co-occurring partial defects affecting more than one gene have not been demonstrated so far in proximal UCDs. Here, we analyzed the mutational spectrum of 557 suspected proximal UCD individuals. We probed oligomerizing forms of NAGS, CPS1 and OTC, and evaluated the surface exposure of residues mutated in heterozygously affected individuals. BN-PAGE and gel-filtration chromatography were employed to discover protein-protein interactions within recombinant enzymes. From a total of 281 confirmed patients, only 15 were identified as "heterozygous-only" candidates (i.e. single defective allele). Within these cases, the only missense variants to potentially qualify as dominant negative triggers were CPS1 p.Gly401Arg and NAGS p.Thr181Ala and p.Tyr512Cys, as assessed by residue oligomerization capacity and surface exposure. However, all three candidates seem to participate in critical intramolecular functions, thus, unlikely to facilitate protein-protein interactions. This interpretation is further supported by BN-PAGE and gel-filtration analyses revealing no multiprotein proximal urea cycle complex formation. Collectively, genetic analysis, structural considerations and in vitro experiments point against a prominent role of dominant negative effects in human proximal UCDs.
Collapse
Affiliation(s)
- Georgios Makris
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland
| | - Matthias Lauber
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland
| | - Véronique Rüfenacht
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland
| | - Corinne Gemperle
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland
| | - Carmen Diez-Fernandez
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland; Nextech Invest, Bahnhofstrasse 18, 8001, Zurich, Switzerland
| | - Ljubica Caldovic
- Center for Genetic Medicine Research, Children's National Hospital, Washington, DC, USA
| | - D Sean Froese
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland
| | - Johannes Häberle
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland.
| |
Collapse
|
9
|
Encarnação M, Coutinho MF, Silva L, Ribeiro D, Ouesleti S, Campos T, Santos H, Martins E, Cardoso MT, Vilarinho L, Alves S. Assessing Lysosomal Disorders in the NGS Era: Identification of Novel Rare Variants. Int J Mol Sci 2020; 21:E6355. [PMID: 32883051 PMCID: PMC7503609 DOI: 10.3390/ijms21176355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/25/2020] [Accepted: 08/28/2020] [Indexed: 11/16/2022] Open
Abstract
Lysosomal storage diseases (LSDs) are a heterogeneous group of genetic disorders with variable degrees of severity and a broad phenotypic spectrum, which may overlap with a number of other conditions. While individually rare, as a group LSDs affect a significant number of patients, placing an important burden on affected individuals and their families but also on national health care systems worldwide. Here, we present our results on the use of an in-house customized next-generation sequencing (NGS) panel of genes related to lysosome function as a first-line molecular test for the diagnosis of LSDs. Ultimately, our goal is to provide a fast and effective tool to screen for virtually all LSDs in a single run, thus contributing to decrease the diagnostic odyssey, accelerating the time to diagnosis. Our study enrolled a group of 23 patients with variable degrees of clinical and/or biochemical suspicion of LSD. Briefly, NGS analysis data workflow, followed by segregation analysis allowed the characterization of approximately 41% of the analyzed patients and the identification of 10 different pathogenic variants, underlying nine LSDs. Importantly, four of those variants were novel, and, when applicable, their effect over protein structure was evaluated through in silico analysis. One of the novel pathogenic variants was identified in the GM2A gene, which is associated with an ultra-rare (or misdiagnosed) LSD, the AB variant of GM2 Gangliosidosis. Overall, this case series highlights not only the major advantages of NGS-based diagnostic approaches but also, to some extent, its limitations ultimately promoting a reflection on the role of targeted panels as a primary tool for the prompt characterization of LSD patients.
Collapse
Affiliation(s)
- Marisa Encarnação
- Research and Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal; (M.E.); (M.F.C.); (L.S.); (D.R.); (L.V.)
- Newborn Screening, Metabolism & Genetics Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal
- Center for the Study of Animal Science, CECA-ICETA, University of Porto, 4051-401 Porto, Portugal
| | - Maria Francisca Coutinho
- Research and Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal; (M.E.); (M.F.C.); (L.S.); (D.R.); (L.V.)
- Center for the Study of Animal Science, CECA-ICETA, University of Porto, 4051-401 Porto, Portugal
| | - Lisbeth Silva
- Research and Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal; (M.E.); (M.F.C.); (L.S.); (D.R.); (L.V.)
- Newborn Screening, Metabolism & Genetics Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal
| | - Diogo Ribeiro
- Research and Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal; (M.E.); (M.F.C.); (L.S.); (D.R.); (L.V.)
| | - Souad Ouesleti
- Biochemical Service, CHU Farhat Hached, 4000 Sousse, Tunisia;
| | - Teresa Campos
- Reference Center for Inherited Metabolic Disorders, University Hospital Centre S. João, 4202-451 Porto, Portugal; (T.C.); (M.T.C.)
| | - Helena Santos
- Department of Pediatrics, Hospital Centre, EPE, 4434-502 V.N. Gaia, Portugal;
| | - Esmeralda Martins
- Oporto Hospital Centre, University of Porto, 4099-001 Porto, Portugal;
| | - Maria Teresa Cardoso
- Reference Center for Inherited Metabolic Disorders, University Hospital Centre S. João, 4202-451 Porto, Portugal; (T.C.); (M.T.C.)
| | - Laura Vilarinho
- Research and Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal; (M.E.); (M.F.C.); (L.S.); (D.R.); (L.V.)
- Newborn Screening, Metabolism & Genetics Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal
- Center for the Study of Animal Science, CECA-ICETA, University of Porto, 4051-401 Porto, Portugal
| | - Sandra Alves
- Research and Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, 4000-055 Porto, Portugal; (M.E.); (M.F.C.); (L.S.); (D.R.); (L.V.)
- Center for the Study of Animal Science, CECA-ICETA, University of Porto, 4051-401 Porto, Portugal
| |
Collapse
|
10
|
Chew HB, Ngu LH. RANBP2 susceptibility to infection-induced encephalopathy: Clinicoradiologic and molecular description in a Malaysian family. Mol Genet Metab Rep 2020; 24:100627. [PMID: 32760653 PMCID: PMC7393314 DOI: 10.1016/j.ymgmr.2020.100627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 11/18/2022] Open
Abstract
Pathogenic variants in RANBP2 cause autosomal dominant familial and recurrent Acute Necrotizing Encephalopathy of Childhood (ANEC). Affected children typically experience a 3-stage disease: a 3 to 5 days prodrome of non-specific febrile illness, acute encephalopathy, and recovery with or without neurological sequelae or death. Neuroradiological finding of bilateral symmetrical thalamic lesions raise the suspicion of this diagnosis. A devastating disease, reported mortality approaches 1/3 of those affected and only approximately 10% of patients recover completely without sequelae. We report a Malaysian family with RANBP2 pathogenic variant c.1754C>T (p.Thr585Met). The clinical presentation and course over a maximum of 7 years, as well as neuroradiological features of the 3 affected children are described. In contrast to the reported high mortality and morbidity, our patients have recovered with minor sequelae. We would like to highlight the absence of pathogenic variants in both parents' blood, raising the possibility of germline mosaicism in one of the parents as the underlying genetic mechanism of inheritance. To our knowledge, this is the first report of germline mosaicism in RANBP2 Susceptibility to Infection-induced Encephalopathy.
Collapse
Affiliation(s)
- H B Chew
- Department of Genetics, Kuala Lumpur Hospital, Jalan Pahang, 50586 Kuala Lumpur, Malaysia
| | - L H Ngu
- Department of Genetics, Kuala Lumpur Hospital, Jalan Pahang, 50586 Kuala Lumpur, Malaysia
| |
Collapse
|
11
|
Bird MJ, Adant I, Windmolders P, Vander Elst I, Felgueira C, Altassan R, Gruenert SC, Ghesquière B, Witters P, Cassiman D, Vermeersch P. Oxygraphy Versus Enzymology for the Biochemical Diagnosis of Primary Mitochondrial Disease. Metabolites 2019; 9:metabo9100220. [PMID: 31658717 PMCID: PMC6835216 DOI: 10.3390/metabo9100220] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 09/27/2019] [Accepted: 10/09/2019] [Indexed: 12/12/2022] Open
Abstract
Primary mitochondrial disease (PMD) is a large group of genetic disorders directly affecting mitochondrial function. Although next generation sequencing technologies have revolutionized the diagnosis of these disorders, biochemical tests remain essential and functional confirmation of the critical genetic diagnosis. While enzymological testing of the mitochondrial oxidative phosphorylation (OXPHOS) complexes remains the gold standard, oxygraphy could offer several advantages. To this end, we compared the diagnostic performance of both techniques in a cohort of 34 genetically defined PMD patient fibroblast cell lines. We observed that oxygraphy slightly outperformed enzymology for sensitivity (79 ± 17% versus 68 ± 15%, mean and 95% CI), and had a better discriminatory power, identifying 58 ± 17% versus 35 ± 17% as “very likely” for oxygraphy and enzymology, respectively. The techniques did, however, offer synergistic diagnostic prediction, as the sensitivity rose to 88 ± 11% when considered together. Similarly, the techniques offered varying defect specific information, such as the ability of enzymology to identify isolated OXPHOS deficiencies, while oxygraphy pinpointed PDHC mutations and captured POLG mutations that were otherwise missed by enzymology. In summary, oxygraphy provides useful information for the diagnosis of PMD, and should be considered in conjunction with enzymology for the diagnosis of PMD.
Collapse
Affiliation(s)
- Matthew J Bird
- Laboratory of Hepatology, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
- Metabolomics Expertise Center, Center for Cancer Biology, CCB-VIB, 3000 Leuven, Belgium.
- Clinical Department of Laboratory Medicine, University Hospitals Leuven, 3000 Leuven, Belgium.
| | - Isabelle Adant
- Laboratory of Hepatology, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
- Department of Pediatrics, University Hospitals Leuven, 3000 Leuven, Belgium.
| | - Petra Windmolders
- Laboratory of Hepatology, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
| | - Ingrid Vander Elst
- Laboratory of Hepatology, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
| | - Catarina Felgueira
- Laboratory of Hepatology, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
| | - Ruqaiah Altassan
- Medical Genetics Department, King Faisal Specialist Hospital and Research Center, KSA MCD, Riyadh 43228, Saudi Arabia.
| | - Sarah C Gruenert
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Medical Center-University of Freiburg, Faculty of Medicine, 79106 Freiburg, Germany.
| | - Bart Ghesquière
- Metabolomics Expertise Center, Center for Cancer Biology, CCB-VIB, 3000 Leuven, Belgium.
- Metabolomics Expertise Center, Department of Oncology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
| | - Peter Witters
- Metabolic Center, University Hospitals Leuven, 3000, Leuven, Belgium.
| | - David Cassiman
- Laboratory of Hepatology, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
- Metabolic Center, University Hospitals Leuven, 3000, Leuven, Belgium.
| | - Pieter Vermeersch
- Clinical Department of Laboratory Medicine, University Hospitals Leuven, 3000 Leuven, Belgium.
- Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
| |
Collapse
|