Association analysis of the pituitary adenylate cyclase-activating polypeptide (PACAP/ADCYAP1) gene in bipolar disorder.

BACKGROUND: Linkage studies in bipolar disorder (BPD) suggest that a susceptibility locus exists on chromosome 18p11. The pituitary adenylate cyclase-activating polypeptide/adenylate cyclase-activating polypeptide 1 (pituitary) (PACAP/ADCYAP1) gene maps to this region. PACAP is a neuropeptide involved in neurotransmission in both the peripheral nervous system and central nervous system and is required for catecholamine secretion. Animal models of PACAP mutations show remarkable behavioral defects, including hyperactivity and increased exploratory behavior.
OBJECTIVE: In this study we tested the hypothesis that genetic variations in the human PACAP gene contribute to BPD.
METHODS: Genotyping of seven single nucleotide polymorphisms (rs1893154; rs2846811; rs8192595; rs2856966; rs928978; rs2231187; rs1610037) was performed in BPD patients (n=570) and healthy controls (n=710). Genotypes and allele frequencies were compared between groups using chi contingency analysis. Linkage disequilibrium between markers was calculated and estimated haplotype frequencies were compared between groups. MAIN
RESULTS: There were no significant differences between groups on the allele, genotype or haplotype level for any of the tested single nucleotide polymorphisms.
CONCLUSION: Our results provide no evidence of an association of the PACAP gene with BPD in this group of patients and controls. Additional studies are necessary to elucidate the BPD susceptibility locus on chromosome 18p.