Chunk #34 — Reasons to be Concerned about the Published cGxE Literature — The Ingredients of cGxE: The Choice of Genetic and Environmental Variables — The Choice of “G”
Large-scale gene finding efforts have moved to systematic screens of the genome (e.g., Sklar et al., 2011; Treutlein et al., 2009; Wray et al., 2012), pathway and network analysis (Weng et al., 2011), and integration with model organism genetics (Zhao et al., 2012) as new avenues for increasing the probability of identifying relevant genes. Further, when a gene of interest is being studied, genetic variants across the gene are usually genotyped in order to capture the many locations across that gene that could be involved2 in altering gene regulation or function and producing different effects on behavior. For example, many early studies genotyped the Taq1A1 polymorphism in DRD2 as a hypothesized biological candidate for a variety of outcomes related to reward deficiency, for which dopamine transmission was thought to play a role (Blum et al., 1990; Meyers et al., 2013; Young, Lawford, Nutting, & Noble, 2004). Subsequently, it was discovered that the polymorphism was actually located in the neighboring gene ANKK1 (Neville, Johnstone, & Walton, 2004). More systematic studies of genetic variation across the region containing ANKK1 and DRD2 have
