A genome wide association study (GWAS) of five major psychiatric disorders found that SNPs within chromosomal regions 3p21 and 10q24, and calcium channel subunit genes CACNA1C and CACNB2 were significantly associated with schizophrenia, depression, bipolar, attention deficit-hyperactivity (ADHD), and autism spectrum disorders (ASD) (35). Here, CACNB2 is linked to major depressive disorder.