Genes in context

Addictions are moderately heritable but influences of diverse genes are stronger on addiction-relevant brain functions modified by these genes, as illustrated by strong effects of functional variants in neuropeptide Y and COMT on brain stress and emotion responses as compared to their weak effects on complex behavior. Vulnerability to addiction is modified by stress and endocrine factors, and effects of several functional variants, for example MAOA, which is endocrine-modified, and FKPBP5, which is stress modified, are stronger in individuals who have received the exposure. Furthermore, rare and uncommon alleles…