The P2RX7 gene (coding for P2X7 purinergic receptor) has been suggested as a novel candidate gene for major depressive disorder (MDD) and bipolar disorder (BPD). The proposed risk allele (G-allele) of the rs2230912 polymorphism results in an amino acid change at the 460th position, marking this genetic variation a possibly functional one. Here we present a case-control analysis of 171 patients diagnosed with MDD or BPD and 178 controls, as well as a dimensional approach using the Hospital Anxiety and Depression Scale (HADS) for studying the Gln460Arg polymorphism of the P2RX7 gene as a genetic risk factor in depression. While case-control analysis did not show significant difference between the groups, a significant association was found between the P2RX7 polymorphism and the HADS scales in the clinical group (MANOVA P = 0.001). Both anxiety and depression scores increased as the number of G-allele increased in the genotype groups (ANOVA for HADS-anxiety: P = 0.01, HADS-depression: P < 0.001). A significant interaction of clinical status and the P2RX7 polymorphism was also found for the depression scale (MANOVA P = 0.025, subsequent ANOVA for anxiety: P = 0.252; depression: P = 0.002). Whereas patients with G-allele-present genotypes showed more elevated depression scores, level of depression in the control group was not affected by the P2RX7 genotype. In conclusion, case-control analysis did not reveal significant results, but using a symptom severity scale we could support the association between depressive disorder and the G-allele of the Gln460Arg polymorphism in the P2RX7 gene.
2008 Wiley-Liss, Inc.