MT-ATP6 mitochondrial disease variants: Phenotypic and biochemical features analysis in 218 published cases and cohort of 14 new cases

Hum Mutat. 2019 May;40(5):499-515. doi: 10.1002/humu.23723. Epub 2019 Mar 4.

Abstract

Mitochondrial complex V (CV) generates cellular energy as adenosine triphosphate (ATP). Mitochondrial disease caused by the m.8993T>G pathogenic variant in the CV subunit gene MT-ATP6 was among the first described human mitochondrial DNA diseases. Due to a lack of clinically available functional assays, validating the definitive pathogenicity of additional MT-ATP6 variants remains challenging. We reviewed all reportedMT-ATP6 disease cases ( n = 218) to date, to assess for MT-ATP6 variants, heteroplasmy levels, and inheritance correlation with clinical presentation and biochemical findings. We further describe the clinical and biochemical features of a new cohort of 14 kindreds with MT-ATP6 variants of uncertain significance. Despite extensive overlap in the heteroplasmy levels of MT-ATP6 variant carriers with and without a wide range of clinical symptoms, previously reported symptomatic subjects had significantly higher heteroplasmy load (p = 2.2 x 10-16 ). Pathogenic MT-ATP6 variants resulted in diverse biochemical features. The most common findings were reduced ATP synthesis rate, preserved ATP hydrolysis capacity, and abnormally increased mitochondrial membrane potential. However, no single biochemical feature was universally observed. Extensive heterogeneity exists among both clinical and biochemical features of distinct MT-ATP6 variants. Improved mechanistic understanding and development of consistent biochemical diagnostic analyses are needed to permit accurate pathogenicity assessment of variants of uncertain significance in MT-ATP6.

Keywords: Leigh syndrome; genotype-phenotype correlation; heteroplasmy; mitochondria; neurogenic ataxia and retinitis pigmentosa.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Alleles
  • Animals
  • Biomarkers
  • Cohort Studies
  • Diagnostic Tests, Routine
  • Genetic Association Studies
  • Genetic Predisposition to Disease*
  • Genetic Testing
  • Genetic Variation*
  • Genotype
  • Humans
  • Inheritance Patterns
  • Mitochondrial Diseases / diagnosis
  • Mitochondrial Diseases / genetics*
  • Mitochondrial Diseases / metabolism
  • Mitochondrial Proton-Translocating ATPases / genetics*
  • Mitochondrial Proton-Translocating ATPases / metabolism
  • Mutation
  • Phenotype

Substances

  • Biomarkers
  • MT-ATP6 protein, human
  • Mitochondrial Proton-Translocating ATPases