Linkage and Association Studies of Substance Use Disorders

Twin, family, and adoption studies have established that genes play a role in the risk for substance use disorders (SUD). Similar to other complex human diseases (e.g., hypertension, major depression, schizophrenia), this high heritability observed in twin studies represents a large genetic contribution to variation in risk for developing a substance use disorder. In an effort to discover those genes and genetic variants contributing to substance use disorder risk, researchers have relied on linkage and association studies in humans. These approaches use molecular genetic technologies to measure genetic variation in individuals and formally assess, using statistical analysis, whether particular variants co-segregate with substance use disorder through families or are more common in SUD patients versus controls. The goal of these approaches is to elucidate SUD neurobiology or identify druggable pathways for SUD treatment, by identifying genes which are linked or associated with SUDs. This chapter reviews these efforts, highlighting the major trends, noteworthy findings and replicating discoveries.