SEROTONIN TRANSPORTER GENE AND RISK FOR BIPOLAR AFFECTIVE-DISORDER - AN ASSOCIATION STUDY IN A SPANISH POPULATION

Background: The serotonin transporter (5-HTT) is an important candidat e gene for the genetic transmission of manic depressive illness. Many studies of patients with affective disorders have found abnormalities in serotonin metabolism and dysregulation of the transporter itself. I n the present study, we hypothesize that genetic variation in the 5-HT T gene (17q11, 1-17q12) may have an effect in the etiology of manic de pression. Methods: To test this hypothesis, we analyzed allele, genoty pe, and haplotype frequencies of two polymorphisms recently described in the 5-HTT gene (a variable number of tandem repeats in intron 2 and a deletion/insertion polymorphism in the transcriptional control regi on) in a sample of 88 patients with manic-depressive illness and 113 c ontrols. Cases and controls were matched for ethnic and geographic ori gin. Results: No associations were found between any of these polymorp hisms, rested individually or as haplotypes, and manic depression. Mor eover, the genetic analysis by sex, presence/absence of psychiatric fa mily history, and age of onset did not reveal significant differences in allele or genotype distributions. Conclusions: Our results suggest that the genetic variability of the 5-HTT gene is not a major risk fac tor for manic depression. (C) 1998 Society of Biological Psychiatry.