A novel MT-CO1 m.6498C>A variation associated with the m.7444G>A mutation in the mitochondrial COI/tRNASer(UCN) genes in a patient with hearing impairment, diabetes and congenital visual loss

► A patient with hearing impairment, maternally inherited diabetes and congenital visual loss was described. ► A whole mitochondrial mutational analysis was performed. ► The m.7444G>A mutation in the MT-CO1/precursor of tRNASer(UCN) genes was found. ► A novel m.6498C>A variation in the MT-CO1 gene was detected. ► The two found mutations could be associated with the multisystemic disorders.