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

Background: The most common form of nonsyndromic neurosensory autosomal recessive deafness, DFNB1, is caused by mutations in the connexin 26 gene ( GJB2 ) on chromosome 13. One mutation, in which one guanosine (G) residue is deleted from a run of 6 Gs (35delG), is found in 40% to 70% of DFNB1 cases and has an expected population frequency of one in 40 to one in 100. Methods and Results: Polymerase chain reaction (PCR)-based tests for the 35delG mutation were developed. They are based on mismatched PCR primers that produce novel Eco RII or Dde I restriction enzyme sites depending on the number of Gs at the 35delG locus. An Eco RII site is generated in the wild-type sequence (6 Gs), but not when the 35delG mutation is present. Alternatively, a Dde I site can be generated so that this enzyme cuts the PCR product when 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.