A novel dominant mutation in the SOX10 gene in a Chinese family with Waardenburg syndrome type II.

Waardenburg syndrome type 2 (WS2) is a rare genetic disorder, characterized by bright blue eyes, moderate to profound hearing loss and pigmental abnormalities of the hair and skin. Between 10 and 20 mutations in the SRY­box 10 (SOX10) gene were previously identified to be associated with WS2. The present study aimed to identify the genetic causes of WS2 in a Chinese family. Clinical and molecular analyses were performed to genetically characterize a Chinese family with two cases of WS2. The clinical data of the proband were collected using a questionnaire. The genomic DNA was extracted from peripheral blood samples of each individual in the family, and 168 candidate genes associated with hearing loss were sequenced using the Illumina HiSeq 2000 and confirmed by Sanger sequencing. A heterozygous nonsense mutation [substitution; position 127; cytosine to thymine (c.127C>T)] was identified in exon 2 of SOX10 (transcript ID: NM_006941.3) in the proband and the mother; however, not in other family members or healthy controls. The novel nonsense heterozygous mutation may cause the replacement of codon 43 [arginine (Arg)] with a stop codon (Arg43stop), leading to premature termination of protein translation. The novel nonsense heterozygous mutation c.127C>T in the SOX10 gene was considered to be the cause of WS2 in the family. This mutation has not been identified in any databases, to the best of the authors' knowledge, including The Single Nucleotide Polymorphism Database, The Human Gene Mutation Database, 1000 Genomes Project and ClinVar and Exome Sequencing Project v. 6500.