Recent evidence indicates that the CHRM2 gene is not only associated with brain oscillations and cognition, but also clinical diagnosis. Significant linkage and association were reported for the CHRM2 gene and a diagnosis of alcohol dependence and depression [191], comorbid alcohol and drug dependence [192], as well as a spectrum of externalizing disorders [193] in the COGA study. Other groups have also replicated these findings, reporting that the CHRM2 gene predisposes to alcohol dependence, drug dependence and affective disorders [194], and major depression in women [195]. Thus, genes important for the expression of the endophenotypes help in identification of genes that increase the susceptibility for risk of alcohol dependence and related disorders [196,197].
