Furthermore, the absent of any functional variants in deafness-related common nuclear genes (GJB2, GJB3, GJB6,SLC26A4 and TRMU) in the matrilineal relatives in these pedigrees suggests that nuclear modified genes may not play an active role in deafness expression, hence, the mt-tRNAGln 4394C>T mutation may enhance the penetrance of m.1555A>G-induced deafness. This evidence concerns the gene GJB6 and deafness.