TJP2 Gene Mutation c.G1012A May Responsible for Congenital Hearing Loss with Incomplete Penetrance in An Iranian Pedigree

Hereditary hearing loss (HHL) comprises half of the congenital deafness which arises from genetic mutations. Mutations in the TJP2 gene, encoding tight junction protein 2, are one of the gene alterations in HHL resulting in an autosomal dominant nonsyndromic form of the disease. An 11-year-old male patient with clinically approved congenital hearing loss was referred to our laboratory. The molecular genetic analysis detected an atypical heterozygous variant -c.1012G > C, p.G338R in exon 5 of the TJP2 gene on chromosome 9 position 71836379 (GRch37). Segregation analysis for his parents has uncovered the same mutation in the patient’s mother, but without any deafness phenotype. This case report provided evidence to demonstrate for the first time the incomplete penetrance of this TJP2 mutation and proposed this mutation as a “likely pathogenic” variant in an Iranian pedigree.