RT Journal Article SR Electronic T1 Association of Guanosine Triphosphate Cyclohydrolase 1 Gene Polymorphisms with Fibromyalgia Syndrome in a Korean Population JF The Journal of Rheumatology JO J Rheumatol FD The Journal of Rheumatology SP jrheum.120929 DO 10.3899/jrheum.120929 A1 Seong-Kyu Kim A1 Seong-Ho Kim A1 Seong-Su Nah A1 Ji Hyun Lee A1 Seung-Jae Hong A1 Hyun-Sook Kim A1 Hye-Soon Lee A1 Hyoun Ah Kim A1 Chung-Il Joung A1 Jisuk Bae A1 Jung-Yoon Choe A1 Shin-Seok Lee YR 2013 UL http://www.jrheum.org/content/early/2013/01/11/jrheum.120929.abstract AB Objective Guanosine triphosphate cyclohydrolase 1 (GCH1) is the rate-limiting enzyme in the synthesis of tetrahydrobiopterin, which is an essential cofactor in nitric oxide (NO) production. Polymorphisms in the GCH1 gene have been implicated in protection against pain sensitivity. The aim of our study was to determine whether single-nucleotide polymorphisms (SNP) in the GCH1 gene affect susceptibility and/or pain sensitivity in fibromyalgia syndrome (FM). Methods A total of 409 patients with FM and 422 controls were enrolled. The alleles and genotypes at 4 positions [rs3783641(T>A), rs841(C>T), rs752688(C>T), and rs4411417(T>C)] in the GCH1 gene were analyzed. The associations of the GCH1 SNP with susceptibility and clinical measures in patients with FM were assessed. Results The frequencies of alleles and genotypes of the 4 SNP did not differ between patients with FM and healthy controls. Among 13 constructed haplotypes, we further examined 4 (CCTT, TTCT, TTCA, and CCTA) with > 1% frequency in both FM and controls. No associations of GCH1 polymorphisms with FM-related activity or severity indexes were found, although the number and total score of tender points in patients with FM differed among the 4 haplotypes (p = 0.03 and p = 0.01, respectively). The CCTA haplotype of GCH1 was associated with significantly lower pain sensitivity and occurred less frequently than the CCTT haplotype in patients with FM (p = 0.04, OR 0.45, 95% CI 0.21–0.96). Conclusion Our study provides evidence that certain GCH1 haplotypes may be protective against susceptibility and pain sensitivity in FM. Our data suggest that NO is responsible for pain sensitivity in the pathogenesis of FM.