COMT and deafness: We did not include the SNPs in the following genes: ACYP2 (coding for an acylphosphatase) [41], SLC31A1 gene coding for the copper transport protein 1 [22], SLC22A2 coding for the organic cation transport protein 2 [21], megalin [24], TPMT and COMT [25, 26, 41] and Mendelian deafness gene [42].