ABSTRACT
Two recent studies reported evidence for association between genetic variation of the positional candidate gene P2RX7 on chromosome 12q24 and bipolar I disorder (BPI) [Barden et al. (2006); Am J Med Genet Part B 141B:374-382; McQuillin et al. (2008); Mol Psychiatry 13:1-7] and one study found association with unipolar major depression (Mdd-UP) [Lucae et al. (2006); Hum Mol Genet 15:2438-2445]. In the present work, we aimed to replicate the SNP that showed the strongest association in the above-mentioned studies, namely rs2230912 (P2RX7-E13A) resulting in a change of the amino acid glutamine to arginine at position 460 (Gln460Arg), in four European bipolar I disorder samples from Germany, Poland, Romania, and Russia totaling 1,445 patients, in a German sample of recurrent Mdd-UP patients (N = 640), and a control sample of 2,006 subjects. We found no allelic or genotypic association between rs2230912 and BPI or Mdd-UP both in the national samples and in the combined European patient sample. Additional studies are needed to clarify the potential involvement of P2RX7 and of SNP rs2230912 in the etiology of major affective disorders.
Subject(s)
Bipolar Disorder/genetics , Depressive Disorder/genetics , Genetic Predisposition to Disease , Polymorphism, Single Nucleotide/genetics , Receptors, Purinergic P2/genetics , White People/genetics , Adult , Alleles , Case-Control Studies , Female , Gene Frequency , Humans , Male , Receptors, Purinergic P2X7ABSTRACT
The neurotransmitter serotonin [5-hydroxytryptamine (5-HT)] controls a broad range of biological functions that are disturbed in affective disorder. In the brain, 5-HT production is controlled by tryptophan hydroxylase 2 (TPH2). In order to assess the possible contribution of TPH2 genetic variability to the aetiology of bipolar affective disorder (BPAD), we systematically investigated common and rare genetic variation in the TPH2 gene through a sequential sequencing and SNP-based genotyping approach. Our study sample comprised two cohorts of BPAD from Germany and Russia, totalling 883 patients and 1300 controls. SNPs located in a haplotype block covering the 5' region of the gene as well as a rare, non-synonymous SNP, resulting in a Pro206Ser substitution, showed significant association with bipolar disorder. The odds ratio for the minor allele in the pooled sample was 1.5 (95% CI 1.2-1.9) for rs11178997 (in the 5'-associated haplotype block) and 4.8 (95% CI 1.6-14.8) for rs17110563 encoding the Pro206Ser substitution. Examination of the functional effects of TPH2 Pro206Ser provided evidence for a reduced thermal stability and solubility of the mutated enzyme, suggesting reduced 5-HT production in the brain as a pathophysiological mechanism in BPAD.
