More specifically, pathogenic mutations in the MTTK gene predominantly result in multisystemic disorders that affect the central nervous system including the MERRF syndrome.7 Jeppesen and colleagues recently described a patient with a heteroplasmic m.8340G>A MTTK variant manifesting as isolated myopathy.8 Here, we report a case of a 39-year-old man harbouring the identical mtDNA point mutation with an extended phenotype of childhood epilepsy, migraines and sensorineural deafness who presented to eye clinic with night blindness and cataracts. This evidence concerns the gene MT-TK and MERRF syndrome.