Serotonin transporter gene polymorphisms: Relation with platelet serotonin level in patients with primary Sjogren's syndrome

•We examine effects of 5-HTT on platelet serotonin primary Sjogren's patients.•Genotyping of 5-HTTLPR, rs25531 and 5-HTTVNTRin2 polymorphisms was performed.•5-HTTVNTRin2 ss polymorphism was associated with decreased PSL in pSS patients.•Sjogren's patients may be distinguished from healthy individuals analyzing the effect of 5-HTTVNTRin2 ss on PSL.•Results suggest involvement of 5-HT system in the pathogenesis of pSS.

Significantly lower platelet serotonin level (PSL) in patients with primary Sjogren's syndrome (pSS) than in healthy controls has been reported in our prior studies. In the present report, we demonstrated effect of functional polymorphisms in the serotonin transporter gene (5-HTT) on PSL. We describe a group of 61 pSS patients and 100 healthy individuals subjects, who received PSL measurement in our prior study. All subjects were genotyped for the promoter 5-HTTLPR (L/S), rs25531 (A/G) and intronic 5-HTTVNTRin2 (l/s) polymorphisms. Overall, the presence of 5-HTTVNTRin2 ss genotype was associated with significantly lower PSL in pSS patients, not in healthy controls. Reduced PSL in pSS patients is in line with hypothesis of association between chronic immunoinflammation and 5-HT system dysregulation, identifying additional mechanisms such as altered 5-HT transport as potential genetic factor contributing to PSL depletion.