Evidence of natural selection for the GWAS SNPs in the GDF5 and IL1RL1/IL18R1 genes. Data were extracted from the 1000 Genomes Selection Browser 1.0 for two natural selection tests: global Fst and integrated haplotype score (iHS). (a) Global Fst values for the SNP rs143384 (Fst = 0.649) and rs224333 (Fst = 0.714) in the GDF5 gene. GWAS signals for the SNPs rs143384 and rs224333 were reported for European and mixed ancestry populations. (b) iHS signals for the SNPs rs2001461 (iHS = 4.54), rs1420103 (iHS = 3.46) and rs6419573 (iHS = 3.34) in the IL18R1/IL1RL1 locus in CEU population. GWAS signals for these SNPs were reported for European ancestry individuals.