The rs3771863 single nucleotide polymorphism of the TACR1 gene is associated to a lower risk of sicca syndrome in fibromyalgia patients.

OBJECTIVES: Fibromyalgia (FM) has been associated with affective spectrum disorders and other chronic pain disorders, which tend to co-occur in individuals and co-aggregate among families. The objective of our study was to investigate the genetic risk factors associated with the presence of related symptoms and with disease severity in subjects affected with FM. METHODS: Two independent cohorts of subjects diagnosed with FM according to the 1990 ACR criteria were studied. A genetic array composed of 320 single nucleotide polymorphisms (SNPs) was analysed in a discovery cohort comprised by 564 patients, and the most suggestive variants were genotyped in a replication cohort, comprised by 397 subjects. The associated conditions and related symptoms analysed were: the presence of depression, sleep disorders, headache, myofascial syndrome, irritable bowel syndrome, chronic fatigue syndrome, vertiginous syndrome, chronic cystitis, and sicca syndrome. FM severity was assessed by the Fibromyalgia Impact Questionnaire and the Hospital Anxiety and Depression Scale. Analyses were adjusted by elapsed time from pain onset, and a meta-analysis was performed to pool the results. RESULTS: Minor allele of the rs3771863 SNP from the TACR1 gene showed a significant association with a lower risk of sicca syndrome (pooled and adjusted OR 0.56, [95%CI 0.42-0.76], p=0.00022). CONCLUSIONS: Our findings indicate a role of the TACR1 gene in the development of sicca syndrome in subjects affected with FM.