In the present investigation, an association between the -240A allele and a reduced risk for MDD was observed, but the genotype distributions of controls were only just in marginal agreement with Hardy-Weinberg equilibrium.The T-T haplotype in the ACE gene was significantly associated with an increased risk for MDD.

ABSTRACT. Several lines of evidence suggest a molecular role of -1438A/G single nucleotide polymorphism in the 5-HTR2A gene promoter (rs6311) in regulating the expression of this gene, making rs6311 polymorphism a promising candidate for an association study. We looked for a possible association between rs6311 polymorphism and major depressive disorder (MDD) in a northeastern Thai population. We included 180 patients with MDD and 183 unrelated healthy controls in our study. Genotyping was performed using PCR-RFLP. We found no significant differences between the two groups with

ABSTRACT. Several lines of evidence suggest that the dopaminergic system is involved in the pathophysiology of major depressive disorder (MDD). Since the dopamine transporter (DAT1, also known as SLC6A3), mediates the active reuptake of dopamine from the synapses and thereby plays a vital role in the regulation of dopaminergic neurotransmission, we looked for a possible association between the C/T single nucleotide polymorphism in intron 14 of the DAT1 gene (also referred to as rs40184) and MDD in a northeastern Thai population. One hundred and seventyeight patients with MDD and 205 unrelated healthy controls were included in our study. Genotyping was performed using our newly established polymerase chain reaction-restriction fragment length polymorphism technique. We found no significant differences in genotype distributions, allele frequencies and allele carrier frequencies when comparing the two groups. Although not significant, we observed more carriers of the C allele (CC+CT genotypes) in healthy controls than in patients with MDD (χ 2  = 3.20, degrees of freedom = 1, P = 0.073, odds ratio = 0.53 [95% confidence interval = 0.28-1.01]). We also detected significant differences in the allele frequencies of rs40184 between healthy subjects of Asian ancestry and those of both Caucasian and African ancestry. We concluded that there is a tendency towards an association between the homozygous TT genotype of the rs40184 single nucleotide polymorphism and an increased risk for MDD in this northeastern Thai population. Possibly, with more samples, this tendency will be confirmed.

Background: Several lines of evidence suggest that the serotonergic system may be involved in the etiology of major depressive disorder (MDD). Objective: Investigate a potential association between the functional polymorphism in the serotonin transporter-linked polymorphic region (5-HTTLPR) and MDD in a northeastern Thai population, and explore the involvement of demographic characteristics in this disorder. Methods: One hundred eighty seven patients with MDD and 207 healthy controls were recruited from the same geographical area into the study. The 5-HTTLPR genotypes were determined using polymerase chain reaction (PCR) and analyzed statically. Results: Significant demographic differences between the two groups were observed, which included age, marital status, occupation, educational background, income, and alcohol use. The allele frequencies of the 5- HTTLPR polymorphism in our studied population were relatively near those of Asian populations, especially Chinese, which was regarded as enormously distinct from those of Caucasians. Nevertheless, our present study found no significant association between this polymorphism and MDD with respect to either genotype distributions or allele frequencies. Conclusion: No involvement of the 5-HTTLPR polymorphism was suggested, but demographic features in MDD were highlighted with respect to this studied population.