Variants in MICOS10 Identified by Whole Genome Sequencing and RNA Sequencing in a New Type of Hepatocerebral Mitochondrial DNA Depletion Syndrome

Abstract

Background: The mitochondrial contact site and cristae organising system (MICOS) complex is required for cristae formation and is composed of seven proteins. Among the genes of MICOS complex, variants of MICOS13, IMMT and APOO have been reported to cause diseases.

Methods and results: We report a case in which whole genome sequencing identified a variant of the MICOS10 gene associated with mitochondrial hepatopathy along with mitochondrial DNA depletion. We identified the deletion g.19596826_19601303del and the single nucleotide variant c.173G>C (p.Cys58Ser). The deletion including exon 1 might have caused complete loss of gene expression, indicating monoallelic expression from RNA sequencing. MIC10 was lost at the protein level in the patient's fibroblasts, and mitochondrial oxygen consumption was impaired. These were restored by overexpression of MICOS10 in the patient's fibroblasts.

Conclusion: Taken together, these findings indicate that MICOS10 is a causative gene for hepatopathy and neuropathy, a disease very similar to that associated with MICOS13.

Keywords: MICOS complex; RNA sequencing; hepatopathy; mitochondrial DNA; whole genome sequencing.