Relationship between FKBP5 polymorphisms and depression symptoms among kidney transplant recipients

Background: Several polymorphisms in FK506 Binding Protein gene (FKBP5) and a history of child abuse have been shown to be associated with an increased risk for posttraumatic stress disorder (PTSD). It has also been demonstrated that the same polymorphisms of FKBP5 are associated with increased recurrence of depressive episodes and rapid response to antidepressant treatment. However, there are only limited numbers of studies replicating the polymorphisms as vulnerability factors for the development of mental illnesses, such as PTSD and depression after stressful life event, especially with a specific incidence, such as kidney transplant surgery. Methods: A retrospective analysis was conducted using the electronic medical records of 131 adult kidney transplant recipients. Depression severity after kidney transplantation was measured by PHQ-9, and stored blood was genotyped for variants in the Serotonin Transporter (SLC6A4), Brain-Derived Neurotrophic Factor, Catecholamine-O-Methyltransferase, Corticotropin-Releasing Hormone Receptor, and FKBP5 genes. Spearman correlations were used to test for association between genetic variants and depression severity. Results: The rare alleles at three out of four SNPs in FKBP5 (rs1360780, rs9296158, and rs9470080) were associated with increased PHQ-9 scores (P<.05), whereas the last FKBP5 SNP (rs3800373) showed a trend of association (P<.10). All four FKBP5 SNPs are in strong linkage disequilibrium. Although in a subgroup of Caucasian non-Hispanic subjects the association was not statistically significant, the direction of association was consistent with that observed in the entire sample as well as in previous studies. Polymorphisms in genes other than FKBP5 were not associated with PHQ-9 scores. Conclusions: Polymorphisms in FKBP5 may be associated with higher depression scores in kidney transplant recipients.