Myosin-7A Mutation Screening in Patients with Prelingual Non-Syndromic Hearing Impairment

ObjectiveTo screen for mutations in myosin-7A gene (MYO7A) in patients with prelingual nonsyndromic hearing impairment. Methods 31 sporadic patients with congenital hearing impairment and 65 patients from 34 families with prelingual hereditary hearing impairment in China were tested in this study, and 100 hearing normal individuals were used as control. Genomic DNA isolated from whole blood of all subjects was subjected to polymerase chain reaction(PCR) to amplify selected exons of MYO7A gene. The PCR products were subsequently screened using single strand conformational polymorphism analysis(SSCP) and direct sequencing when the fragments showed an abnormal electrophoretic pattern.ResultsGgA transition at position 617 in exon 7, which would produce an A206G amino acid substitution, was detected in two patients but in none of the unaffected members in the families. This heterozygous missense mutation happened within a highly conserved heptapeptide sequence of MYO7A protein, and is closely relevant to preligual nonsyndromic deafness.ConclusionsThe A206G substitution is possibly a new mutation to cause preligual nonsyndromic hearing impairment. Our results provide evidence that exon 7 of MYO7A is a mutational hotspot in genetic hearing impairment.