CHRND on chromosome 2 harbors a fourth significant locus, with an additional interesting, though only nominally significant, uncorrelated locus in the neighboring gene CHRNG. Efforts to replicate these findings in independent samples would be of great interest. The CHRND-CHRNG cluster lies at the end of chromosome 2q in a region of linkage that has been persistently reported in the literature for nicotine dependence (Straub et al., 1999) and other addiction phenotypes (Agrawal et al., 2008; Gelernter et al., 2005; Gelernter et al., 2006). The γ subunit is known only to be fetally expressed and replaced by ε in late fetal development (Mishina et al., 1986), suggesting an unexpected mechanism for influencing addiction risk if indeed CHRNG is involved.
