1
|
Meldau S, Ackermann S, Riordan G, van der Watt GF, Spencer C, Raga S, Khan K, Blackhurst DM, van der Westhuizen FH. A novel mitochondrial DNA variant in MT-ND6: m.14430A>C p.(Trp82Gly) identified in a patient with Leigh syndrome and complex I deficiency. Mol Genet Metab Rep 2024; 39:101078. [PMID: 38571879 PMCID: PMC10987324 DOI: 10.1016/j.ymgmr.2024.101078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/23/2024] [Accepted: 03/25/2024] [Indexed: 04/05/2024] Open
Abstract
Leigh syndrome is a severe progressive mitochondrial disorder mainly affecting children under the age of 5 years. It is caused by pathogenic variants in any one of more than 75 known genes in the nuclear or mitochondrial genomes. A 19-week-old male infant presented with lactic acidosis and encephalopathy following a 2-week history of irritability, neuroregression and poor weight gain. He was hypotonic with pathological reflexes, impaired vision, and nystagmus. Brain MRI showed extensive bilateral symmetrical T2 hyperintense lesions in basal ganglia, thalami, and brainstem. Metabolic workup showed elevated serum alanine, and heavy lactic aciduria with increased ketones, fumarate, malate, and alpha-ketoglutarate as well as reduced succinate on urine organic acid analysis. Lactic acidemia persisted, with only a marginally elevated lactate:pyruvate ratio (16.46, ref. 0-10). He demised at age 7 months due to respiratory failure. Exome sequencing followed by virtual gene panel analysis for pyruvate metabolism and mitochondrial defects could not identify any nuclear cause for Leigh syndrome. Mitochondrial DNA (mtDNA) genome sequencing revealed 88% heteroplasmy for a novel variant, NC_012920.1(MT-ND6):m.14430A>C p.(Trp82Gly), in blood DNA. This variant was absent from the unaffected mother's blood, fibroblast, and urine DNA, and detected at a level of 5% in her muscle DNA. Mitochondrial respiratory chain analysis revealed markedly reduced mitochondrial complex I activity in patient fibroblasts (34% of parent and control cells), and reduced NADH-linked respirometry (less than half of parental and control cells), while complex II driven respirometry remained intact. The combined clinical, genetic, and biochemical findings suggest that the novel MT-ND6 variant is the likely cause of Leigh syndrome in this patient. The mitochondrial ND6 protein is a subunit of complex I. An interesting finding was the absence of a significantly elevated lactate:pyruvate ratio in the presence of severe lactatemia, which directed initial diagnostic efforts towards excluding a pyruvate metabolism defect. This case highlights the value of a multidisciplinary approach and complete genetic workup to diagnosing mitochondrial disorders in South African patients.
Collapse
Affiliation(s)
- Surita Meldau
- National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
- Division of Chemical Pathology, University of Cape Town, Cape Town, South Africa
| | - Sally Ackermann
- Private Practice, Constantiaberg Mediclinic, Cape Town, South Africa
| | - Gillian Riordan
- Division of Paediatric Neurology, Dept of Paediatrics and Child Health, University of Cape Town, Red Cross War Memorial Children's Hospital, Cape Town, South Africa
| | - George F. van der Watt
- National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
- Division of Chemical Pathology, University of Cape Town, Cape Town, South Africa
| | - Careni Spencer
- Department of Medicine, Groote Schuur Hospital and Division of Human Genetics, University of Cape Town, Cape Town, South Africa
| | - Sharika Raga
- Division of Paediatric Neurology, Dept of Paediatrics and Child Health, University of Cape Town, Red Cross War Memorial Children's Hospital, Cape Town, South Africa
- Neuroscience Institute, University of Cape Town, South Africa
- International Centre for Genomic Medicine in Neuromuscular Diseases Study, University College London, London, United Kingdom
| | - Kashief Khan
- National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
- Division of Chemical Pathology, University of Cape Town, Cape Town, South Africa
| | - Dee M. Blackhurst
- Division of Chemical Pathology, University of Cape Town, Cape Town, South Africa
| | | |
Collapse
|
2
|
Bisschoff M, Smuts I, Dercksen M, Schoonen M, Vorster BC, van der Watt G, Spencer C, Naidu K, Henning F, Meldau S, McFarland R, Taylor RW, Patel K, Fassad MR, Vandrovcova J, Wanders RJA, van der Westhuizen FH. Clinical, biochemical, and genetic spectrum of MADD in a South African cohort: an ICGNMD study. Orphanet J Rare Dis 2024; 19:15. [PMID: 38221620 PMCID: PMC10789041 DOI: 10.1186/s13023-023-03014-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 12/20/2023] [Indexed: 01/16/2024] Open
Abstract
BACKGROUND Multiple acyl-CoA dehydrogenase deficiency (MADD) is an autosomal recessive disorder resulting from pathogenic variants in three distinct genes, with most of the variants occurring in the electron transfer flavoprotein-ubiquinone oxidoreductase gene (ETFDH). Recent evidence of potential founder variants for MADD in the South African (SA) population, initiated this extensive investigation. As part of the International Centre for Genomic Medicine in Neuromuscular Diseases study, we recruited a cohort of patients diagnosed with MADD from academic medical centres across SA over a three-year period. The aim was to extensively profile the clinical, biochemical, and genomic characteristics of MADD in this understudied population. METHODS Clinical evaluations and whole exome sequencing were conducted on each patient. Metabolic profiling was performed before and after treatment, where possible. The recessive inheritance and phase of the variants were established via segregation analyses using Sanger sequencing. Lastly, the haplotype and allele frequencies were determined for the two main variants in the four largest SA populations. RESULTS Twelve unrelated families (ten of White SA and two of mixed ethnicity) with clinically heterogeneous presentations in 14 affected individuals were observed, and five pathogenic ETFDH variants were identified. Based on disease severity and treatment response, three distinct groups emerged. The most severe and fatal presentations were associated with the homozygous c.[1067G > A];c.[1067G > A] and compound heterozygous c.[976G > C];c.[1067G > A] genotypes, causing MADD types I and I/II, respectively. These, along with three less severe compound heterozygous genotypes (c.[1067G > A];c.[1448C > T], c.[740G > T];c.[1448C > T], and c.[287dupA*];c.[1448C > T]), resulting in MADD types II/III, presented before the age of five years, depending on the time and maintenance of intervention. By contrast, the homozygous c.[1448C > T];c.[1448C > T] genotype, which causes MADD type III, presented later in life. Except for the type I, I/II and II cases, urinary metabolic markers for MADD improved/normalised following treatment with riboflavin and L-carnitine. Furthermore, genetic analyses of the most frequent variants (c.[1067G > A] and c.[1448C > T]) revealed a shared haplotype in the region of ETFDH, with SA population-specific allele frequencies of < 0.00067-0.00084%. CONCLUSIONS This study reveals the first extensive genotype-phenotype profile of a MADD patient cohort from the diverse and understudied SA population. The pathogenic variants and associated variable phenotypes were characterised, which will enable early screening, genetic counselling, and patient-specific treatment of MADD in this population.
Collapse
Affiliation(s)
- Michelle Bisschoff
- Focus area for Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - Izelle Smuts
- Department of Paediatrics, Steve Biko Academic Hospital, University of Pretoria, Pretoria, South Africa
| | - Marli Dercksen
- Centre for Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - Maryke Schoonen
- Focus area for Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - Barend C Vorster
- Centre for Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - George van der Watt
- Division of Chemical Pathology, National Health Laboratory Services, University of Cape Town, Cape Town, South Africa
| | - Careni Spencer
- Division of Human Genetics, Department of Medicine, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa
| | - Kireshnee Naidu
- Division of Neurology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - Franclo Henning
- Division of Neurology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - Surita Meldau
- Division of Chemical Pathology, National Health Laboratory Services, University of Cape Town, Cape Town, South Africa
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Krutik Patel
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Mahmoud R Fassad
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Jana Vandrovcova
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Ronald J A Wanders
- Department of Clinical Chemistry, Laboratory Genetic Metabolic Diseases, Amsterdam University Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | | |
Collapse
|
3
|
Raga SV, Wilmshurst JM, Smuts I, Meldau S, Bardien S, Schoonen M, van der Westhuizen FH. A case for genomic medicine in South African paediatric patients with neuromuscular disease. Front Pediatr 2022; 10:1033299. [PMID: 36467485 PMCID: PMC9713312 DOI: 10.3389/fped.2022.1033299] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 10/31/2022] [Indexed: 11/18/2022] Open
Abstract
Paediatric neuromuscular diseases are under-recognised and under-diagnosed in Africa, especially those of genetic origin. This may be attributable to various factors, inclusive of socioeconomic barriers, high burden of communicable and non-communicable diseases, resource constraints, lack of expertise in specialised fields and paucity of genetic testing facilities and biobanks in the African population, making access to and interpretation of results more challenging. As new treatments become available that are effective for specific sub-phenotypes, it is even more important to confirm a genetic diagnosis for affected children to be eligible for drug trials and potential treatments. This perspective article aims to create awareness of the major neuromuscular diseases clinically diagnosed in the South African paediatric populations, as well as the current challenges and possible solutions. With this in mind, we introduce a multi-centred research platform (ICGNMD), which aims to address the limited knowledge on NMD aetiology and to improve genetic diagnostic capacities in South African and other African populations.
Collapse
Affiliation(s)
- Sharika V Raga
- Department of Neurophysiology, Department of Paediatric Neurology, Red Cross War Memorial Children's Hospital, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Jo Madeleine Wilmshurst
- Department of Neurophysiology, Department of Paediatric Neurology, Red Cross War Memorial Children's Hospital, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Izelle Smuts
- Department of Paediatrics, Steve Biko Academic Hospital, University of Pretoria, Pretoria, South Africa
| | - Surita Meldau
- Division of Chemical Pathology, Department of Pathology, National Health Laboratory Service and University of Cape Town, Cape Town, South Africa
| | - Soraya Bardien
- Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.,South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Cape Town, South Africa
| | - Maryke Schoonen
- Human Metabolomics, North-West University, Potchefstroom, South Africa
| | | |
Collapse
|
4
|
Swart C, Meldau S, Centner CM, Marais AD, Omar F. Validation of PHASE for deriving N-acetyltransferase 2 haplotypes in the Western Cape mixed ancestry population. Afr J Lab Med 2020; 9:988. [PMID: 33392048 PMCID: PMC7756977 DOI: 10.4102/ajlm.v9i1.988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 09/14/2020] [Indexed: 11/17/2022] Open
Abstract
Background There is a shortage of data on the accuracy of statistical methods for the prediction of N-acetyltransferase 2 (NAT2) haplotypes in the mixed ancestry population of the Western Cape. Objective This study aimed to identify the NAT2 haplotypes and assess the accuracy of PHASE version 2.1.1 in assigning NAT2 haplotypes to a mixed ancestry population from the Western Cape. Methods This study was conducted between 2013 and 2016. The NAT2 gene was amplified and sequenced from the DNA of 100 self-identified mixed ancestry participants. Haplotyping was performed by molecular and computational techniques. Agreement was assessed between the two techniques. Results Haplotypes were assigned to 93 samples, of which 67 (72%) were ambiguous. Haplotype prediction by PHASE demonstrated 94.6% agreement (kappa 0.94, p < 0.001) with those assigned using molecular techniques. Five haplotype combinations (from 10 chromosomes) were incorrectly predicted, four of which were flagged as uncertain by the PHASE software. Only one resulted in the assignment of an incorrect acetylation phenotype (intermediate to slow), although the software flagged this for further analysis. The most common haplotypes were NAT2*4 (28%) followed by NAT2*5B (27.4%), NAT2*6A (21.5%) and NAT2*12A (7.5%). Four rare single nucleotide variants (c.589C>T, c.622T>C, c.809T>C and c.387C>T) were detected. Conclusion PHASE accurately predicted the phenotype in 92 of 93 samples (99%) from genotypic data in our mixed ancestry sample population, and is therefore a suitable alternative to molecular methods to individualise isoniazid therapy in this high burden tuberculosis setting.
Collapse
Affiliation(s)
- Celeste Swart
- Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,National Health Laboratory Service (NHLS), Groote Schuur Hospital, Cape Town, South Africa
| | - Surita Meldau
- National Health Laboratory Service (NHLS), Groote Schuur Hospital, Cape Town, South Africa.,Division of Chemical Pathology, University of Cape Town, Cape Town, South Africa
| | - Chad M Centner
- Division of Medical Microbiology, University of Cape Town, Cape Town, South Africa.,National Health Laboratory Service (NHLS), Medical Microbiology, Groote Schuur Hospital, Cape Town, South Africa
| | - Adrian D Marais
- Division of Chemical Pathology, University of Cape Town, Cape Town, South Africa
| | - Fierdoz Omar
- Division of Chemical Pathology, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
5
|
Meldau S, Owen EP, Khan K, Riordan GT. Mitochondrial molecular genetic results in a South African cohort: divergent mitochondrial and nuclear DNA findings. J Clin Pathol 2020; 75:34-38. [PMID: 33115810 DOI: 10.1136/jclinpath-2020-207026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/09/2020] [Accepted: 10/11/2020] [Indexed: 12/22/2022]
Abstract
AIMS Mitochondrial diseases form one of the largest groups of inborn errors of metabolism. The birth prevalence is approximately 1/5000 in well-studied populations, but little has been reported from Sub-Saharan Africa. The aim of this study was to describe the genetics underlying mitochondrial disease in South Africa. METHODS An audit was performed on all mitochondrial disease genetic testing performed in Cape Town, South Africa. RESULTS Of 1614 samples tested for mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) variants in South Africa between 1994 and 2019, there were 155 (9.6 %) positive results. Pathogenic mtDNA variants accounted for 113 (73%)/155, from 96 families. Mitochondrial encephalopathy with lactic acidosis and stroke-like episodes, 37 (33%)/113, Leber's hereditary optic neuropathy, 26 (23%)/113, and single large mtDNA deletions, 22 (20%)/113, accounted for 76%. Thirty eight of 42 nDNA-positive results were homozygous for the MPV17 pathogenic variant c.106C>T (p.[Gln36Ter, Ser25Profs*49]) causing infantile neurohepatopathy, one of the largest homozygous groups reported in the literature. The other nDNA variants were in TAZ1, CPT2, BOLA3 and SERAC1. None were identified in SURF1, POLG or PDHA1. CONCLUSIONS Finding a large group with a homozygous nuclear pathogenic variant emphasises the importance of looking for possible founder effects. The absence of other widely described pathogenic nDNA variants in this cohort may be due to reduced prevalence or insufficient testing. As advances in therapeutics develop, it is critical to develop diagnostic platforms on the African subcontinent so that population-specific genetic variations can be identified.
Collapse
Affiliation(s)
- Surita Meldau
- Division of Chemical Pathology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa .,Chemical Pathology, National Health Laboratory Services, Groote Schuur Hospital, Cape Town, South Africa
| | - Elizabeth Patricia Owen
- Division of Chemical Pathology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Chemical Pathology, National Health Laboratory Services, Groote Schuur Hospital, Cape Town, South Africa
| | - Kashief Khan
- Chemical Pathology, National Health Laboratory Services, Groote Schuur Hospital, Cape Town, South Africa
| | - Gillian Tracy Riordan
- Division of Paediatric Neurology, Department of Paediatrics and Child Health, University of Cape Town, Cape Town, Western Cape, South Africa.,Red Cross War Memorial Children's Hospital, Cape Town, South Africa
| |
Collapse
|
6
|
Roberts L, Julius S, Dawlat S, Yildiz S, Rebello G, Meldau S, Pillay K, Esterhuizen A, Vorster A, Benefeld G, da Rocha J, Beighton P, Sellars SL, Thandrayen K, Pettifor JM, Ramesar RS. Renal dysfunction, rod-cone dystrophy, and sensorineural hearing loss caused by a mutation in RRM2B. Hum Mutat 2020; 41:1871-1876. [PMID: 32827185 DOI: 10.1002/humu.24094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 08/03/2020] [Accepted: 08/14/2020] [Indexed: 12/29/2022]
Abstract
More than two decades ago, a recessive syndromic phenotype affecting kidneys, eyes, and ears, was first described in the endogamous Afrikaner population of South Africa. Using whole-exome sequencing of DNA from two affected siblings (and their carrier parents), we identified the novel RRM2B c.786G>T variant as a plausible disease-causing mutation. The RRM2B gene is involved in mitochondrial integrity, and the observed change was not previously reported in any genomic database. The subsequent screening revealed the variant in two newly presenting unrelated patients, as well as two patients in our registry with rod-cone dystrophy, hearing loss, and Fanconi-type renal disease. All patients with the c.786G>T variant share an identical 1.5 Mb haplotype around this gene, suggesting a founder effect in the Afrikaner population. We present ultrastructural evidence of mitochondrial impairment in one patient, to support our thesis that this RRM2B variant is associated with the renal, ophthalmological, and auditory phenotype.
Collapse
Affiliation(s)
- Lisa Roberts
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Stephanie Julius
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Shrinav Dawlat
- Department of Human Genetics, National Health Laboratory Servicexs, Groote Schuur Hospital, Cape Town, South Africa
| | - Safiye Yildiz
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - George Rebello
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Surita Meldau
- Department of Human Genetics, National Health Laboratory Servicexs, Groote Schuur Hospital, Cape Town, South Africa.,Division of Chemical Pathology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Komala Pillay
- Division of Anatomical Pathology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Alina Esterhuizen
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Human Genetics, National Health Laboratory Servicexs, Groote Schuur Hospital, Cape Town, South Africa
| | - Alvera Vorster
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Gameda Benefeld
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Jorge da Rocha
- Sydney Brenner Institute for Molecular Bioscience, Division of Human Genetics, National Health Laboratory Service, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Peter Beighton
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Sean L Sellars
- Division of Otorhinolaryngology, Department of Surgery, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Kebashni Thandrayen
- Department of Paediatrics, Chris Hani Baragwanath Academic Hospital and School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - John M Pettifor
- Department of Paediatrics, Chris Hani Baragwanath Academic Hospital and School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Raj S Ramesar
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
7
|
Meldau S, Fratter C, Bhengu LN, Sergeant K, Khan K, Riordan GT, Berman PAM. Pitfalls of relying on genetic testing only to diagnose inherited metabolic disorders in non-western populations - 5 cases of pyruvate dehydrogenase deficiency from South Africa. Mol Genet Metab Rep 2020; 24:100629. [PMID: 32742935 PMCID: PMC7387837 DOI: 10.1016/j.ymgmr.2020.100629] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 11/26/2022] Open
Abstract
Pyruvate dehydrogenase complex (PDHC) deficiencies are a group of mainly infantile onset disorders stemming from defects in pyruvate catabolism. They are characterised by severe lactic acidosis and progressive neurodegeneration.Although the PDHA1 gene is implicated in most cases of PDHC deficiency worldwide, no pathogenic variants have been reported in South African patients to date, despite availability of PDHA1 sequencing in the state diagnostic setting. Methods DNA from five patients with low to absent PDHC activity in fibroblasts were subjected to PDHC deficiency gene panel analysis. Included in the panel were: PDHA1, PDHB, DLAT, DLD, PDHX, BOLA3, GLRX5, IBA57, LIAS, LIPT1, LIPT2, NFU1, PDP1, PDP2, SLC19A2, SLC19A3, SLC25A19, SLC25A26, TPK1 and FBXL4. Results No pathogenic variants were identified in 4 out of 5 cases investigated. A homozygous frame-shift mutation was detected in the BOLA3 gene in one patient, supporting a diagnosis of multiple mitochondrial dysfunction syndrome type 2. Discussion A single, novel, homozygous BOLA3 frame-shift mutation was detected in a black South African child with severe neurodegenerative disease and very low to absent PDHC enzyme activity. This finding of a homozygous mutation in a patient from a non-consanguineous background may indicate a need for further investigation in clinically similar cases as well as heterozygous carrier rates in unaffected individuals from the same ethnic background.The paucity of identifiable mutations in 4 out of 5 South African patients with confirmed PDHC deficiency highlights the dangers in relying on Western population based genetic panels for diagnosing rare metabolic disease in genetically understudied populations.
Collapse
Affiliation(s)
- Surita Meldau
- National Health Laboratory Service (NHLS), Cape Town, South Africa.,Division of Chemical Pathology, Department of Pathology, University of Cape Town (UCT), Cape Town, South Africa
| | - Carl Fratter
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Louisa Ntombenhle Bhengu
- Department of Human Genetics, National Health Laboratory Service and School of Pathology, University of Witwatersrand, Johannesburg, South Africa
| | - Kate Sergeant
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Kashief Khan
- National Health Laboratory Service (NHLS), Cape Town, South Africa
| | - Gillian Tracy Riordan
- Paediatric Neurology Department of Paediatrics and Child Health Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
| | - Peter Allan Minham Berman
- National Health Laboratory Service (NHLS), Cape Town, South Africa.,Division of Chemical Pathology, Department of Pathology, University of Cape Town (UCT), Cape Town, South Africa
| |
Collapse
|
8
|
Ng YS, Lax NZ, Maddison P, Alston CL, Blakely EL, Hepplewhite PD, Riordan G, Meldau S, Chinnery PF, Pierre G, Chronopoulou E, Du A, Hughes I, Morris AA, Kamakari S, Chrousos G, Rodenburg RJ, Saris CGJ, Feeney C, Hardy SA, Sakakibara T, Sudo A, Okazaki Y, Murayama K, Mundy H, Hanna MG, Ohtake A, Schaefer AM, Champion MP, Turnbull DM, Taylor RW, Pitceathly RDS, McFarland R, Gorman GS. MT-ND5 Mutation Exhibits Highly Variable Neurological Manifestations at Low Mutant Load. EBioMedicine 2018; 30:86-93. [PMID: 29506874 PMCID: PMC5952215 DOI: 10.1016/j.ebiom.2018.02.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/03/2018] [Accepted: 02/12/2018] [Indexed: 01/06/2023] Open
Abstract
Mutations in the m.13094T>C MT-ND5 gene have been previously described in three cases of Leigh Syndrome (LS). In this retrospective, international cohort study we identified 20 clinically affected individuals (13 families) and four asymptomatic carriers. Ten patients were deceased at the time of analysis (median age of death was 10years (range: 5·4months-37years, IQR=17·9years). Nine patients manifested with LS, one with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), and one with Leber hereditary optic neuropathy. The remaining nine patients presented with either overlapping syndromes or isolated neurological symptoms. Mitochondrial respiratory chain activity analysis was normal in five out of ten muscle biopsies. We confirmed maternal inheritance in six families, and demonstrated marked variability in tissue segregation, and phenotypic expression at relatively low blood mutant loads. Neuropathological studies of two patients manifesting with LS/MELAS showed prominent capillary proliferation, microvacuolation and severe neuronal cell loss in the brainstem and cerebellum, with conspicuous absence of basal ganglia involvement. These findings suggest that whole mtDNA genome sequencing should be considered in patients with suspected mitochondrial disease presenting with complex neurological manifestations, which would identify over 300 known pathogenic variants including the m.13094T>C.
Collapse
Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Nichola Z Lax
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Paul Maddison
- Department of Neurology, Queen's Medical Centre, Nottingham, UK
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Philippa D Hepplewhite
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Gillian Riordan
- Paediatric Neurology Department, Red Cross War Memorial Children's Hospital, Cape Town, South Africa
| | - Surita Meldau
- Division of Chemical Pathology, Faculty of Health Sciences, University of Cape Town, South Africa; National Health Laboratory Service, Cape Town, South Africa
| | - Patrick F Chinnery
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK; Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK
| | - Germaine Pierre
- Department of Inherited Metabolic Disease, Division of Women's and Children's Services, University Hospitals Bristol NHS Foundation Trust, Bristol, UK
| | - Efstathia Chronopoulou
- Department of Inherited Metabolic Disease, Division of Women's and Children's Services, University Hospitals Bristol NHS Foundation Trust, Bristol, UK
| | - Ailian Du
- Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Imelda Hughes
- Royal Manchester Children's Hospital, Central Manchester University Hospitals NHS Foundation Trust, UK
| | - Andrew A Morris
- Institute of Human Development, University of Manchester, Manchester M13 9WL, UK; Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, UK
| | - Smaragda Kamakari
- Ophthalmic Genetics Unit, OMMA, Institute of Ophthalmology, Athens, Greece
| | - Georgia Chrousos
- Pediatric Ophthalmology Department, MITERA Children's Hospital, Athens, Greece
| | - Richard J Rodenburg
- Radboud Center for Mitochondrial Medicine, Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christiaan G J Saris
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Catherine Feeney
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Steven A Hardy
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Takafumi Sakakibara
- Department of Pediatrics, Nara Medical University Hospital, Nara 634-8522, Japan
| | - Akira Sudo
- Department of Pediatrics, Sapporo City General Hospital, Sapporo 060-8604, Japan
| | - Yasushi Okazaki
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo 113-8421, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba 266-0007, Japan
| | - Helen Mundy
- Evelina London Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Akira Ohtake
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama 350-0495, Japan
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Mike P Champion
- Evelina London Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert D S Pitceathly
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.
| |
Collapse
|
9
|
Meldau S, De Lacy R, Riordan G, Goddard E, Pillay K, Fieggen K, Marais A, Van der Watt G. Identification of a single MPV17 nonsense-associated altered splice variant in 24 South African infants with mitochondrial neurohepatopathy. Clin Genet 2018; 93:1093-1096. [DOI: 10.1111/cge.13208] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/12/2017] [Accepted: 12/16/2017] [Indexed: 12/13/2022]
Affiliation(s)
- S. Meldau
- Division of Chemical Pathology, Department of Pathology, Groote Schuur and Red Cross War Memorial Children's Hospital; University of Cape Town and National Health Laboratory Service; Cape Town South Africa
| | - R.J. De Lacy
- Division of Paediatric Gastroenterology, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital; University of Cape Town; Cape Town South Africa
| | - G.T.M. Riordan
- Division of Paediatric Neurology, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital; University of Cape Town; Cape Town South Africa
| | - E.A. Goddard
- Division of Paediatric Gastroenterology, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital; University of Cape Town; Cape Town South Africa
| | - K. Pillay
- Division of Anatomical Pathology, Department of Pathology, Red Cross War Memorial Children's Hospital; University of Cape Town and National Health Laboratory Service; Cape Town South Africa
| | - K.J. Fieggen
- Division of Human Genetics, Department of Medicine, Groote Schuur Hospital; University of Cape Town; Cape Town South Africa
| | - A.D. Marais
- Division of Chemical Pathology, Department of Pathology, Groote Schuur and Red Cross War Memorial Children's Hospital; University of Cape Town and National Health Laboratory Service; Cape Town South Africa
| | - G.F. Van der Watt
- Division of Chemical Pathology, Department of Pathology, Groote Schuur and Red Cross War Memorial Children's Hospital; University of Cape Town and National Health Laboratory Service; Cape Town South Africa
| |
Collapse
|
10
|
Freercks R, Meldau S, Jones E, Ensor J, Weimers-Willard C, Rayner B. Liddle's syndrome in an African male due to a novel frameshift mutation in the beta-subunit of the epithelial sodium channel gene. Cardiovasc J Afr 2017; 28:e4-e6. [PMID: 29144530 PMCID: PMC5730729 DOI: 10.5830/cvja-2017-012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 01/12/2017] [Indexed: 11/06/2022] Open
Abstract
Resistant hypertension is a common clinical problem in South Africa and is frequently associated with low renin and aldosterone levels, especially in black Africans. In South Africa, novel variants in the epithelial sodium channel (ENaC) have been described to be associated with varying degrees of hypokalaemia and hypertension due to primary sodium retention. We report here a case of Liddle's syndrome due to a novel c.1709del11 (p.Ser570Tyrfs*20) deletion in the beta-subunit of the ENaC in a young black African male. We discuss the likely pathogenesis of hypertension in this setting as well as the treatment options available in South Africa aimed at the ENaC. This case highlights the need for vigilance in detecting and appropriately treating low-renin and low-aldosterone hypertension in view of the frequency of the described variants of the ENaC channel in our country. Specific therapy such as amiloride should be made more widely available.
Collapse
Affiliation(s)
- Robert Freercks
- Division of Nephrology and Hypertension, Livingstone Hospital, Port Elizabeth, South Africa; Department of Medicine, Division of Nephrology and Hypertension, University of Cape Town, Cape Town, South Africa.
| | - Surita Meldau
- Division of Chemical Pathology, University of Cape Town and National Health Laboratory Service, Cape Town, South Africa
| | - Erika Jones
- Department of Medicine, Division of Nephrology and Hypertension, University of Cape Town, Cape Town, South Africa
| | - Jason Ensor
- Division of Nephrology and Hypertension, Livingstone Hospital, Port Elizabeth, South Africa; Department of Medicine, Division of Nephrology and Hypertension, University of Cape Town, Cape Town, South Africa
| | | | - Brian Rayner
- Department of Medicine, Division of Nephrology and Hypertension, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
11
|
van der Westhuizen FH, Sinxadi PZ, Dandara C, Smuts I, Riordan G, Meldau S, Malik AN, Sweeney MG, Tsai Y, Towers GW, Louw R, Gorman GS, Payne BA, Soodyall H, Pepper MS, Elson JL. Understanding the Implications of Mitochondrial DNA Variation in the Health of Black Southern African Populations: The 2014 Workshop. Hum Mutat 2016; 36:569-71. [PMID: 25764011 DOI: 10.1002/humu.22789] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 03/07/2015] [Indexed: 11/07/2022]
|
12
|
Haarburger D, Renison R, Meldau S, Eastman R, van der Watt G. Teenaged siblings with progressive neurocognitive disease. Clin Chem 2013; 59:1160-4. [PMID: 23894159 DOI: 10.1373/clinchem.2012.190710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- David Haarburger
- Division of Chemical Pathology, Groote Schuur and Red Cross War Memorial Children's Hospitals, National Health Laboratories Service, University of Cape Town, South Africa
| | | | | | | | | |
Collapse
|
13
|
van der Watt G, Owen EP, Berman P, Meldau S, Watermeyer N, Olpin SE, Manning NJ, Baumgarten I, Leisegang F, Henderson H. Glutaric aciduria type 1 in South Africa-high incidence of glutaryl-CoA dehydrogenase deficiency in black South Africans. Mol Genet Metab 2010; 101:178-82. [PMID: 20732827 DOI: 10.1016/j.ymgme.2010.07.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/27/2010] [Accepted: 07/27/2010] [Indexed: 11/30/2022]
Abstract
Glutaric Aciduria type 1 (GA 1) is an inherited disorder of lysine and tryptophan catabolism that typically manifests in infants with acute cerebral injury associated with intercurrent illness. We investigated the clinical, biochemical and molecular features in 14 known GA 1 patients in South Africa, most of whom were recently confirmed following the implementation of sensitive urine organic acid screening at our laboratory. Age at diagnosis ranged from 3days to 5years and poor clinical outcome reflected the delay in diagnosis in all but one patient. Twelve patients were unrelated black South Africans of whom all those tested (n=11) were found homozygous for the same A293T mutation in the glutaryl-CoA dehydrogenase (GCDH) gene. Excretion of 3-hydroxyglutarate (3-OHGA) was >30.1μmol/mmol creatinine (reference range <2.5) in all cases but glutarate excretion varied with 5 patients considered low excretors (glutarate <50μmol/mmol creatinine). Fibroblast GCDH activity was very low or absent in all of five cases tested. Heterozygosity for the A293T mutation was found 1 in 36 (95% CI; 1/54 - 1/24) unrelated black South African newborns (n=750) giving a predicted prevalence rate for GA 1 of 1 in 5184 (95% CI; 1/11664 - 1/2304) in this population. GA 1 is a treatable but often missed inherited disorder with a previously unrecognised high carrier frequency of a single mutation in the South African black population.
Collapse
Affiliation(s)
- George van der Watt
- Division of Chemical Pathology, Groote Schuur and Red Cross Children's Hospitals, University of Cape Town, Cape Town, South Africa.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Dheda K, van Zyl-Smit RN, Meldau R, Meldau S, Symons G, Khalfey H, Govender N, Rosu V, Sechi LA, Maredza A, Semple P, Whitelaw A, Wainwright H, Badri M, Dawson R, Bateman ED, Zumla A. Quantitative lung T cell responses aid the rapid diagnosis of pulmonary tuberculosis. Thorax 2009; 64:847-53. [DOI: 10.1136/thx.2009.116376] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
15
|
Dheda K, van Zyl-Smit RN, Sechi LA, Badri M, Meldau R, Meldau S, Symons G, Semple PL, Maredza A, Dawson R, Wainwright H, Whitelaw A, Vallie Y, Raubenheimer P, Bateman ED, Zumla A. Utility of quantitative T-cell responses versus unstimulated interferon- for the diagnosis of pleural tuberculosis. Eur Respir J 2009; 34:1118-26. [DOI: 10.1183/09031936.00005309] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|