CYP2D6 and Bradycardia: Studies have observed that homozygotes and heterozygotes for the SNP rs16947 (CYP2D6 *2) may increase the risk of developing bradycardia induced by timolol, and that the SNP rs769258 (CYP2D6 *35 duplication-negative) is notably more prevalent in Caucasian UMs [34,36,37,38].