Identification of novel variants in the Cx29 gene of nonsyndromic hearing loss patients using buccal cells and restriction fragment length polymorphism method.

The crucial role of gap junctions, which are composed of connexin (Cx) protein, in auditory functions has been confirmed by numerous studies. Cx29 is a relatively new member of the Cx protein family. In this article, we report variants of the Cx29 gene in 253 unrelated Taiwanese patients with nonsyndromic hearing loss. Thirteen (5.14%) of the 253 patients had variants of Cx29. Five sequence changes (c.43C-->G, c.230G-->C, c.525T-->G, c.781 + 62G-->A and c.*2T-->G) in the Cx29 gene were detected in the study, of which 3 (c.43C-->G, c.230G-->C and c.525T-->G) were novel variants. One novel compound heterozygote missense variant, c.[43C-->G(+) 230G-->C], was identified in the Cx29 gene carried by 1 patient, and this variant appears to have been inherited from the mother's chromosome. In addition, for diagnostic purposes, we developed a restriction fragment length polymorphism method using NaeI and StyI to identify c.43C-->G and c.525T-->G specific variants of the Cx29 gene, respectively. On the basis of the above results, we suggest that the c.[43C-->G(+)230G-->C] compound heterozygous variant of Cx29 may be a risk factor for the development of hearing loss in Taiwanese and that the restriction fragment length polymorphism method developed will be clinically useful in identifying variants of the Cx29 gene in patients with hearing loss.