A novel compound heterozygous mutation of the MTO1 gene associated with complex oxidative phosphorylation deficiency type 10

Background: The mitochondrial tRNA translation optimization 1 (MTO1) gene, which is closely related to defective mitochondrial oxidative phosphorylation, is an evolutionarily conserved protein expressed in high energy-demanding tissues and is associated with complex oxidative phosphorylation deficiency type 10 (COXPD10) in humans. Related cases and studies are still scarce and have not been reported in the Chinese region.

Materials and methods: Detailed clinical assessment was applied to the patient. Based on next-generation sequencing technology, we performed whole-exome sequencing of the patient and the parents. Sanger sequencing was used for validation. Bioinformatics software and protein simulations were used to predict the pathogenicity of the variants.

Results: The patient was diagnosed with a possible association with mitochondrial disease according to the clinical manifestations and physical examination. A novel frameshift mutation c.344delA (p. Asn115Thrfs*11) and a novel point mutation c.1055C > T (p. Thr352Met) in the MTO1 gene were identified. They were found to cause abnormal changes in amino acids and the protein by biochemical tools, indicating it may be pathogenic.

Conclusion: We present two novel and possibly pathogenic variants in the MTO1 gene in a Chinese Han family.