Spectrum of myo7a mutations in an indigenous south african population further elucidates the nonsyndromic autosomal recessive phenotype of dfnb2 to include both homozygous and compound heterozygous mutations

Rosemary Ida Kabahuma, Wolf Dieter Schubert, Christiaan Labuschagne, Denise Yan, Susan Halloran Blanton, Michael Sean Pepper, Xue Zhong Liu

Research output: Contribution to journalArticlepeer-review

Abstract

MYO7A gene encodes unconventional myosin VIIA, which, when mutated, causes a phenotypic spectrum ranging from recessive hearing loss DFNB2 to deaf-blindness, Usher Type 1B (USH1B). MYO7A mutations are reported in nine DFNB2 families to date, none from sub-Saharan Africa.In DNA, from a cohort of 94 individuals representing 92 families from the Limpopo province of South Africa, eight MYO7A variations were detected among 10 individuals. Family studies identified homozygous and compound heterozygous mutations in 17 individuals out of 32 available family members. Four mutations were novel, p.Gly329Asp, p.Arg373His, p.Tyr1780Ser, and p.Pro2126Leufs*5. Two variations, p.Ser617Pro and p.Thr381Met, previously listed as of uncertain significance (ClinVar), were confirmed to be pathogenic. The identified mutations are predicted to interfere with the conformational properties of myosin VIIA through interruption or abrogation of multiple interactions between the mutant and neighbouring residues. Specifically, p.Pro2126Leufs*5, is predicted to abolish the critical site for the interactions between the tail and the motor domain essential for the autoregulation, leaving a non-functional, unregulated protein that causes hearing loss. We have identified MYO7A as a possible key deafness gene among indigenous sub-Saharan Africans. The spectrum of MYO7A mutations in this South African population points to DFNB2 as a specific entity that may occur in a homozygous or in a compound heterozygous state.

Original languageEnglish (US)
Article number274
Pages (from-to)1-26
Number of pages26
JournalGenes
Volume12
Issue number2
DOIs
StatePublished - Feb 2021
Externally publishedYes

Keywords

  • Compound heterozygous
  • DFNB2
  • Homozygous
  • MYO7A gene
  • Recessive hearing loss
  • South African
  • Spectrum of MYO7A mutations
  • Sub-Saharan Africa

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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