Genome-wide association study identifies ITGB3 as a QTL for whole blood serotonin

Serotonin has been implicated in common disorders involving the central nervous, gastrointestinal, cardiovascular, and pulmonary systems. We describe the first genome-wide screen to identify quantitative trait loci (QTLs) influencing whole blood serotonin in 567 members of a single large pedigree, using a novel association-based mapping approach. We identified an association between the beta3 integrin (ITGB3) Leu33Pro polymorphism on 17q21 and whole blood serotonin levels (P-value = 9.8 x 10(-5)). This variant explained the evidence for linkage in this region when included as a covariate in the linkage analysis ( change in LOD from 1.87 to 0.16), indicating that ITGB3 may be an important serotonin QTL.