Variants validation
To elucidate the disease-causing genes, we obtained venous whole blood samples from the individual and her parents for whole-exome and mitochondrial genomic sequencing. According to the instructions of the manufacturer, the patient’s and parents’ DNA were extracted using the DNA extraction kit (Beyotime Biotechnology, China). Whole-exome and mitochondrial genomic sequencing were performed by Aegicare (China). The candidate disease-causing gene was screened according to the criteria mentioned before (Richards et al., 2015). Total DNA extracted from patient and the parents was amplified by 2×Taq Master Mix (Vazyme, China) according to the manufacturer’s instruction, and the variants were verified by sanger sequencing. The primers are as follows: DupT-F: TTTGTTTACT GTCCTATCTTAAGCAC, dupT-R: ACCTGATTAGGAGGATTGTTGC, 82-2-F: AAG CCAATGT CTAACAGATAAT, 82-2-R: CTTGTTTCCCCCATTCTT. Then segregation study was performed base on the mendelian law.