GJB6 and deafness: Moreover, the frequency of TT mutant genotype was twofold in the affected samples in comparison to that reported for the control group (31% vs. 15%) indicating a statistically significant relationship between the aforementioned polymorphism and HL (P=0.04) (11).Regarding polymorphism rs7333214 of GJB6 gene, there was no significant correlation between the frequency of this polymorphism and deafness (P=0.1).