A Multisystem Mitochondrial Disease Caused by a Novel MT-TL1 mtDNA Variant: A Case Report

J Neuromuscul Dis. 2023;10(1):119-123. doi: 10.3233/JND-221526.


Background: Mitochondrial tRNA (MTT) genes are hotspot for mitochondrial DNA mutation and are responsible of half mitochondrial disease. MTT mutations are associated with a broad spectrum of phenotype often with complex multisystem involvement and complex genotype-phenotype correlations. MT-TL1 mutations, among which the m.3243A>G mutation is the most frequent, are associated with myopathy, maternal inherited diabetes and deafness, MELAS, cardiomyopathy, and focal segmental glomerulosclerosis.

Case study: Here we report the case of an Italian 49-years old female presenting with encephalomyopathy, chronic proteinuric kidney disease and a new heteroplasmic m.3274_3275delAC MT-TL1 gene mutation.

Conclusions: Our case demonstrates a systemic mitochondrial disease caused by the heteroplasmic m.3274_3275delAC MT-TL1 gene mutation, not yet described in the literature. A mitochondrial disease should be suspected in case of complex multisystem phenotypes, including steroid-resistant nephrotic syndrome with multisystemic involvement.

Keywords: glomerulosclerosis; kidney disease; mitochondrial diseases; mitochondrial myopathies; mtDNA.

Publication types

  • Case Reports

MeSH terms

  • DNA, Mitochondrial / genetics
  • Female
  • Humans
  • MELAS Syndrome* / genetics
  • Mitochondria / genetics
  • Mitochondrial Diseases* / complications
  • Mitochondrial Diseases* / genetics
  • Mutation


  • DNA, Mitochondrial