GJB2 and GJB6 mutations in hereditary recessive non-syndromic hearing impairment in Cameroon

Abstract

This study aimed to investigate GJB2 (connexin 26) and GJB6 (connexin 30) mutations associated with familial non-syndromic childhood hearing impairment (HI) in Cameroon. We selected only families segregating HI, with at least two affected individuals and with strong evidence of non-environmental causes. DNA was extracted from peripheral blood, and the entire coding region of GJB2 was interrogated using Sanger sequencing. Multiplex PCR and Sanger sequencing were used to analyze the prevalence of the GJB6-D3S1830 deletion. A total of 93 patients, belonging to 41 families, were included in the analysis. Hearing impairment was sensorineural in 51 out of 54 (94.4%) patients. Pedigree analysis suggested autosomal recessive inheritance in 85.4% (35/41) of families. Hearing impairment was inherited in an autosomal dominant and mitochondrial mode in 12.2% (5/41) and 2.4% (1/41) of families, respectively. Most HI participants were non-syndromic (92.5%; 86/93). Four patients from two families presented with type 2 Waardenburg syndrome, and three cases of type 2 Usher syndrome were identified in one family. No GJB2 mutations were found in any of the 29 families with non-syndromic HI. Additionally, the GJB6-D3S1830 deletion was not identified in any of the HI patients. This study confirms that mutations in the GJB2 gene and the del(GJB6-D13S1830) mutation do not contribute to familial HI in Cameroon.