We then hypothesized that different SNPs may belong to the same functional haplotype associated with increased pain sensitivity. The analysis of the constructed LD matrix using the Haploview program showed that the 23 analyzed SNPs were located in two separate haplotype blocks (Supplementary Material, Fig. S3). SNPs rs7776341–rs3798678 are in Block I and SNPs rs563649–rs497332 are in Block II, which is consistent with previously published reports (57). rs563649 (C/T) is situated on the border of two haploblocks, displaying very high LD with SNPs in both haploblocks (Supplementary Material, Fig. S3).
