A novel insertion-induced frameshift mutation of the SLC26A4 gene in a Korean family with Pendred syndrome.

Pendred syndrome (PS) is an autosomal recessive disorder characterized by congenital bilateral sensorineural hearing loss, goiter, and incomplete iodide organification. Patients with PS also have structural anomalies of the inner ear such as enlarged vestibular aqueducts (EVA) and Mondini's malformation. The goiter, which is a major clinical manifestation of PS, usually develops around adolescence. PS is caused by biallelic mutations of the SLC26A4 gene, while nonsyndromic bilateral EVA is associated with zero or one SLC26A4 mutant allele. We report here a Korean family including a young female with PS who had goiter and progressive, fluctuating sensorineural hearing loss that could be partially recovered by oral steroid treatment. Genetic investigation revealed compound heterozygous mutations for p.R677AfsX11, a novel frameshift mutation, and p.H723R in the SLC26A4 gene. Our findings provide detailed information regarding the distribution of mutant alleles for PS and may serve as a foundation for studies to comprehend the genetic portion of syndromic hearing loss.