To investigate possible association of FS with single nucleotide polymorphisms (SNPs) in prostaglandin-endoperoxide synthase-2 (prostaglandin G/H synthase-2; PTGS2/cyclooxygenase-2; COX2) gene involving in thermoregulatory pathway, eight SNPs, rs689465, rs689466, rs20417, rs13306038, rs201931599, rs689470, rs4648306 and rs4648308, along with 2 previously reported variations in IL1RN (86-bp VNTR) and IL10 (rs1900872) were genotyped and utilized for case-control association studies on 35 FS and 31 non-FS controls.