Sex differences in the influence of COMT Val158Met on alcoholism and smoking in plains American Indians.

Background: Alcoholism and heavy smoking are highly comorbid and are cotransmitted in the general U.S. population; however little is known about comorbidity in American Indians.

BDNF variation and mood disorders: a novel functional promoter polymorphism and Val66Met are associated with anxiety but have opposing effects.

The brain-derived neurotrophic factor (BDNF) gene is critical for neuronal function and survival, and is likely to be important in psychiatric disorders. In this study, we used single-nucleotide polymorphism (SNP) discovery, functional analyses, and genetic association studies to better understand the potential role of BDNF sequence variation in behavior. Screening 480 unrelated individuals for SNPs and genotyping was performed in US Caucasian, American Indian, and African American populations.