In the 30 symptomatic non-MELAS patients, all except 2 had confirmatory genetic testing with the classic MTTL1 m.3242A > G mutation; of the two who did not, one had m.13513G > A in ND5 gene and had MIDD phenotype and the other had biopsy confirmation and had encephalopathy without SLE. This evidence concerns the gene MT-TL1 and maternally-inherited diabetes and deafness.