Genetic association study of individual symptoms in depression

The heritability of some individual depressive symptoms has been well established. However, the causal genes related to individual depressive symptoms and genetic effects on the courses of individual depressive symptoms are still unclear. We examined these issues in 241 Korean patients who met the DSM-IV-TR criteria for major depression. Patients entered a 12-week clinical trial with antidepressants. A total of 1399 single-nucleotide polymorphisms (SNPs) of 79 candidate genes were assessed. The rs557762 and the TT haplotype in the 11th haplotype block of the GRIA3 gene were associated with feelings of guilt in females. The GGCCGGGC haplotype in the first haplotype block of TPH1 was significantly associated with middle insomnia. The ACAG haplotype in the 13th haplotype block of the GRIK2 gene was associated with somatic anxiety. Moreover, the effect of the rs557762 on guilt significantly varied across times. Our results indicate that there are associations between particular gene polymorphisms and some individual depressive symptoms. These results could contribute to understanding the biological mechanisms of depression. (C) 2012 Elsevier Ireland Ltd. All rights reserved.