Is FKBP5 a genetic marker of affective psychosis? A case control study and analysis of disease related traits

Background: A dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis has been proposed as an important pathogenic factor in depression. Genetic variants of FKBP5, a protein of the HPA system modulating the glucocorticoid receptor, have been reported to be genetically associated with improved response to medical treatment and an increase of depressive episodes. Methods: We examined three single nucleotide polymorphisms (SNPs) in FKBP5, rs4713916 in the proposed promoter region, rs1360780 in the second intron and rs3800373 in the 3'-untranslated region (3'-UTR), in a case-control study of Caucasian origin (affective psychosis: n = 248; controls: n = 188) for genetic association and association with disease related traits. Results: Allele and genotype frequencies of rs4713916, rs1360780 and rs3800373 were not significantly different between cases and controls. Two three-locus haplotypes, G-C-T and A-T-G, accounted for 86.2% in controls. Odds ratios were not increased between cases and controls, except the rare haplotype G-C-G (OR 6.81), representing 2.1% of cases and 0.3% of controls. The frequency of rs4713916AG in patients deviated from expected Hardy-Weinberg equilibrium, the genotype AA at rs4713916 in monopolar depression (P = 0.011), and the two-locus haplotype rs1360780T - rs3800373T in the total sample (overall P = 0.045) were nominally associated with longer continuance of disease. Conclusion: Our data do not support a significant genetic contribution of FKBP5 polymorphisms and haplotypes to affective psychosis, and the findings are inconclusive regarding their contribution to disease-related traits.