Additionally, there are three SNPs (rs1045642, rs2032582 and rs1128503) within the most widely studied of these genes, ABCB1, which have been suggested to have a potential impact on OS in PCM and which may form a haplotype in ABCB1. rs1045642 in ABCB1 appears to be the only SNP affecting OS within the PCM patients studied, with minimal linkage disequilibrium demonstrated between it and rs2032582 and rs1128503.