These results suggest that the CHRNB3-A6 locus contains multiple variants affecting risk for vulnerability to cocaine and nicotine dependence as well as bipolar disorder, suggesting that they have pleiotropic effects.
These results suggest that the CHRNB3-A6 locus contains multiple variants affecting risk for vulnerability to cocaine and nicotine dependence as well as bipolar disorder, suggesting that they have pleiotropic effects.
In the investigation of pleiotropic effects of these SNPs on bipolar disorder, two highly correlated synonymous SNPs in CHRNB3, rs4952 and rs4953, were significantly associated with bipolar disorder (odds ratio 1.7, 95% confidence interval: 1.2-2.4, P=0.001).
Our results suggest that (i) bipolar disorder does not modify the association between nicotine dependence and nicotinic receptor subunit genes, and (ii) variants in CHRNB3/CHRNA6 are independently associated with bipolar disorder.
Molecular genetics and developmental studies have identified 21 genes in this region (ADRA1A, ARHGEF10, CHRNA2, CHRNA6, CHRNB3, DKK4, DPYSL2, EGR3, FGF17, FGF20, FGFR1, FZD3, LDL, NAT2, NEF3, NRG1, PCM1, PLAT, PPP3CC, SFRP1 and VMAT1/SLC18A1) that are most likely to contribute to neuropsychiatric disorders (schizophrenia, autism, bipolar disorder and depression), neurodegenerative disorders (Parkinson's and Alzheimer's disease) and cancer.