Genetic heterogeneity in erythrokeratodermia variabilis: novel mutations in the connexin gene GJB4 (Cx30.3) and genotype-phenotype correlations.
Direct evidence of the critical physiological role of connexins (Cxs) has come through the associations of several human diseases with pathogenic mutations in specific Cx genes. Currently, mutations in genes coding for five Cx proteins (Cx26, Cx30, Cx31, Cx32, and Cx43) have been shown to cause sensorineural hearing loss. Cx45 is another gap junction protein, coded by the GJA7 gene. To investigate the possible contribution of GJA7 mutations to deafness, we sequenced the GJA7 gene in 341 unrelated probands with nonsyndromic hearing loss from Turkey, South Africa, United Kingdom, United States, and China. Three nucleotide variants not affecting the amino acid sequence, c.213C>T, c.906C>T, and c.912G>T, and one missense change, c.889C>A (p.D297N), were found. None of the identified changes appeared to be pathogenic. Our data suggest that GJA7 alterations have no or low genetic relevance in nonsyndromic hearing loss in these populations.