Identification of a Novel Variant in MT-CO3 Causing MELAS.

Abstract

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a maternally inherited mitochondrial disease. Most cases of MELAS are caused by the m.3243A > G variant in the MT-TL1 gene encoding tRNALeu(UUR). However, the genetic cause in 10% of patients with MELAS is unknown. We investigated the pathogenicity of the novel mtDNA variant m.9396G > A/MT-CO3 (p.E64K), which affects an extremely conserved amino acid in the CO3 subunit of mitochondrial respiratory chain (MRC) complex IV (CIV) in a patient with MELAS. Biochemical assays of a muscle biopsy confirmed remarkable CIV deficiency, and pathological examination showed ragged red fibers and generalized COX non-reactive muscle fibers. Transfer of the mutant mtDNA into cybrids impaired CIV assembly, followed by remarkable mitochondrial dysfunction and ROS production. Our findings highlight the pathogenicity of a novel m.9396G > A variant and extend the spectrum of pathogenic mtDNA variants.

• Authors: Manting Xu, Robert Kopajtich, Matthias Elstner, Zhaoxia Wang, Zhimei Liu, Junling Wang, Holger Prokisch, Fang Fang
• Journal: Frontiers in genetics (Front Genet) Vol. 12 Pg. 638749 ( 2021) ISSN: 1664-8021 [Print] Switzerland
• PMID: 34054915 (Publication Type: Journal Article)
• Copyright: Copyright © 2021 Xu, Kopajtich, Elstner, Wang, Liu, Wang, Prokisch and Fang.