Association study of nicotinic-receptor variants and major depressive disorder

Background: Depressive patients are more likely to smoke than the general p opulation and nicotine was found to reduce the incidence and severity of de pressive symptoms in many studies. These findings suggest that nicotinic ac etylcholine receptors (nAChRs) may be implicated in major depressive disord er. We tested the hypothesis that the allelic variant, 2 bp deletion, of th e partially duplicated alpha7 nAChR gene confers susceptibility to major de pressive disorder. Methods: We genotyped alpha7 nAChR in 72 patients with m ajor depressive disorder and 103 normal controls. Results: The distribution of the partially duplicated alpha7 nAChR genotypes (P = 0.027) and alleles (P = 0.037) suggests a modest difference between depressive patients and c ontrols. Limitations: The -2 bp allele is thought to be present only in the duplicated exon 6, and the impact of the partially duplicated alpha7 nAChR and its -2 bp variant remain to be determined. Conclusions: The -2 bp alle le of partially duplicated alpha nAChR may have an influence on the risk fo r development of major depressive disorder. The levels of significance achi eved are modest and the findings must be replicated in other studies. (C) 2 001 Elsevier Science BY All rights reserved.