Accumulating evidence, including that from clinical, epidemiological, and molecular genetic studies, suggests that some genetic risk factors are shared between neuropsychiatric disorders. Genome-wide studies have identified rare copy-number variants that confer risk of several neuropsychiatric disorders including autism, attention deficit-hyperactivity disorder, epilepsy, intellectual disability, and schizophrenia.39 Our analyses of 14 SNPs previously identified as being genome-wide significantly associated with schizophrenia and bipolar disorder suggest that some loci identified in studies of individual disorders have broader phenotypic effects. Our results suggest a diversity of findings, with some SNPs showing diagnostic specificity and others pleiotropic effects on two or more of the five disorders.
