The overall detection rate of disease-causing mutations was 43.6% (127 of 291 patients): 80 (27.5%) patients by Sanger sequencing, three (1.0%) patients with MELAS syndrome by PCR-RFLP of the MT-TL1 gene, four (1.4%) patients by WES, and 40 (13.7%) patients by TES. The gene discussed is TNFSF15; the disease is MELAS syndrome.