Resumo

Objective The aim of the present study was to examine the association between polymorphisms in the TPH2 gene and late-onset depression in the Brazilian population. Depression is one of the most common psychiatric disorders among the elderly and has a high social impact with high suicide rates and poor prognosis of comorbidities. The tryptophan hydroxylase type II (TPH2) gene has been associated with many mood disorders especially with major depression. Tph2 is a rate-limiting enzyme in the biosynthesis of serotonin and polymorphisms in this gene might result in changes of brain serotonin synthesis. Methods We genotyped 8 tag-SNPs in the TPH2 gene in 84 outpatients with diagnosis of late-onset depression and 79 individuals belonging to the healthy comparison group to investigate an association between the TPH2 gene and late-onset depression. The symptoms was measured using the DSM-IV, a structured interview using, MINI-PLUS and Geriatric Depression Scale (GDS). Results Our findings suggested an association between tagSNP rs4565946 heterozygous C/T (p= 0,009; χ2= 6,722) and decreased risk of late-onset depression. The tagSNP rs11179000 ancestral homozygous A/A (p = 0,01, odds ratio (OR)= 3,5 (1,08-10,3), χ2= 7.32) and increase risk of late-onset depression. A strong association of ancestral allele A and increase risk of late-onset depression was demonstrated for the tagSNP rs11179000 (p-value= 0,005, odds ratio (OR)= 1,98 (1,22-3,22), χ2= 7.801). Conclusion We found the statistically significant association between two tagSNPs and late-onset depression. Our results support the hypothesis that the TPH2 gene is associated with late onset depression. However, further studies are needed to clarify this association.