Two molecular assays for the rapid and inexpensive detection of GJB2 and GJB6 mutations.

Abstract

The hypoacusia can be classified in two clinical forms: Syndromic (SHL) and Nonsyndromic (NSHL). In particular, the NSHL describes the 70-80% of hypoacusia cases and it is mainly due to genetic factors, which are causative of the deafness at the birth. The genetic hypoacusia presents different inheritance patterns: autosomal dominant (20%), autosomal recessive (80%), X-linked (1%), and mitochondrial (1%), respectively. To date, about 35 deafness-causative genes have been identified and most of them codify for connexin transmembrane proteins. Approximately 1:2500 children with NSHL carries mutations in the GJB2 and GJB6 (13q12) genes, which code for connexin 26 (Cx26) and connexin 30 (Cx30), respectively. In the Caucasian population, the most common mutations are 35delG, M34T and 167delT, and D13S1830. Given the frequency distribution of the four mutations in the Caucasian population and the pathogenic connection with NSHL, the development of accurate, rapid, and "low-cost" molecular assays should be strongly encouraged. To this purpose, we set up two different molecular assays (namely the Cx26 and Cx26-30 molecular assays) for the fast and inexpensive detection of 35delG, M34T, 167delT, and D13S1830 mutations. Both the molecular approaches showed to be accurate, sensitive, reproducible, and "low-cost" alternatives for the proper evaluation of the GJB2 and GJB6 genes, which are causative of NSHL. In conclusion, the Cx26 and Cx26-30 molecular assays can be applied to individual, preconception, prenatal, or postnatal screening for the causative-mutations of NSHL.