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Clinical, biochemical, and genetic spectrum of MADD in a South African cohort: an ICGNMD study

Lookup NU author(s): Professor Bobby McFarlandORCiD, Professor Robert Taylor, Krutik PatelORCiD, Dr Mahmoud FassadORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2024, The Author(s).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.

Publication metadata

Author(s): 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

Publication type: Article

Publication status: Published

Journal: Orphanet Journal of Rare Diseases

Year: 2024

Volume: 19

Issue: 1

Online publication date: 14/01/2024

Acceptance date: 20/12/2023

Date deposited: 29/01/2024

ISSN (electronic): 1750-1172

Publisher: BioMed Central Ltd


DOI: 10.1186/s13023-023-03014-8

PubMed id: 38221620


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Funder referenceFunder name
203105/Z/16/ZWellcome Trust
MR/S005021/1Medical Research Council (MRC)