A simple PCR test to detect the common 35delG mutation in the connexin 26 gene

Background: The most common form of nonsyndromic neurosensory autosomal rec essive deafness, DFNB1, is caused by mutations in the connexin 26 gene (GJB 2) on chromosome 13. One mutation, in which one guanosine (G) residue is de leted from a run of 6 Gs (35delC), is found in 40% to 70% of DFNB1 cases an d has an expected population frequency of one in 40 to one in 100. Methods and Results: Polymerase chain reaction (PCR)-based tests for the 35 delG mutation were developed. They are based on mismatched PCR primers that produce novel EcoRII or DdeI restriction enzyme sites depending on the num ber of Gs at the 35delG locus. An EcoRII site is generated in the wild-type sequence (6 Gs), but not when the 35delG mutation is present. Alternativel y, a DdeI site can be generated so that this enzyme cuts the PCR product wh en the 35delG mutation is present, but not the wild-type sequence. Conclusions: These tests enable a quick and reliable screen for the common 35delG mutation.