Targeted next-generation sequencing identified a novel variant of SOX10 in a Chinese family with Waardenburg syndrome type 2.

OBJECTIVE: Waardenburg syndrome type 2 (WS2) is an autosomal dominant syndrome, characterized by bright blue eyes, hearing loss, and depigmented patches of hair and skin. It exhibits high phenotypic and genetic heterogeneity. We explored the molecular etiology in a Chinese family with WS2. METHODS: We recruited a three-generation family with three affected members. Medical history was obtained from all family members who underwent detailed physical examinations and audiology tests. Genomic DNA was extracted from peripheral blood of each individual, and 139 candidate genes associated with hearing loss were sequenced using Illumina HiSeq 2000 (Illumina Inc., San Diego, CA, USA) and verified by Sanger sequencing. RESULTS: Genetic evaluation revealed a novel nonsense heterozygous variant, NM_006941.4: c.342G>A (p.Trp114Ter) in exon 2 of the SOX10 gene in the three affected patients; no unaffected family member carried the variation. We did not detect the variation in 500 Chinese individuals with normal hearing or in 122 unrelated Chinese families with hearing loss, suggesting that it was specific to our patients. CONCLUSIONS: We identified a novel heterozygous nonsense variation in a family with syndromic hearing loss and WS2. Our findings expand the pathogenic spectrum and strengthen the clinical diagnostic role of SOX10 in patients with WS2.

Targeted next-generation sequencing identifies a novel frameshift EYA1 variant causing branchio-otic syndrome in a Chinese family.

OBJECTIVE: To evaluate the genotype-phenotype correlation of branchio-otic syndrome (BOS) in a Chinese family. METHODS: The proband in this study was an 18-month-old boy with hearing loss, preauricular pit, and branchial fistula without a renal anomaly. We collected blood samples from 6 family members, including 4 who were affected by the syndrome. Targeted next-generation sequencing and Sanger sequencing were performed to identify pathogenic mutations in this family. RESULTS: Pedigree analysis indicated that the mode of inheritance in the family was consistent with the autosomal dominant pattern. Hearing loss was the most common manifestation, occurring in 4 patients. Other findings included preauricular pits (n=2), cervical fistulas (n=3) and abnormal pinnae (n=4). None of the patients had renal anomalies. Evaluation by pure-tone audiometry and temporal bone imaging demonstrated bilateral mixed hearing loss, as well as middle ear and inner ear deformities, in two patients. Mutational analysis of candidate genes in the selected patients led to the identification of a novel frameshift variant NM_000503.4: c.1075_1077delinsAT (p.Gly359Ilefs*7) in the EYA1 gene. CONCLUSIONS: The EYA1 c.1075_1077delinsAT mutation is the causative variant in the Chinese family with BOS, although the penetrance is variable within patients.