CACNA1A and type 2 diabetes mellitus: These informative trait associations represent diverse disease phenotypes, including neuropsychiatric traits (e.g., HTT, depression; CACNA1A, positive affect; ATXN7, schizophrenia), metabolic disorders (e.g., ATXN2, type 1 diabetes; HTT/ATXN7, type 2 diabetes), and autoimmune disorders (e.g., ATXN1, multiple sclerosis; ATXN1, systemic lupus erythematosus).