Objectives: Differences in serotonin transporter (SERT) expression and function produced by gene polymorphisms are associated with several behavioral and psychiatric traits. Two polymorphic regions of SERT gene: a 44-base-pair (bp) insertion / deletion polymorphism in the promoter region (SERTPR), and variable number of tandem repeats (VNTR) in second intron (SERT-in2) have been characterized. In this study we investigated the frequency distribution of polymorphic variants of short (S, s) and long (L, l) alleles, genotypes and haplotypes of SERTPR, and SERTin2, in patients with major depressive disorder (MDD) and compared it with results obtained from the Croatian healthy population.
Subjects and methods: one hundred and fourteen patients who fulfilled DSM-IV criteria for a diagnosis of MDD were included in the study. Comparisons were made with the results obtained for 120 healthy volunteers representing a mixed Croatian population. SERT genotyping was performed by the PCR (polymerase-chain reaction) method.
Results: The frequency distribution of L and S alleles and genotypes of SERTPR was not statistically different between MDD patients and control participants. The proportion of SERT-in2 short (s) alleles was significantly higher among MDD patients in comparison to healthy subjects (p = 0.04).
Conclusion: "s" allele variant in the intron 2 of SERT gene could be associated with susceptibility to MDD.