Our results show a small but significant rg SNP value between schizophrenia and ASD. A lower genetic correlation between schizophrenia and ASD than between schizophrenia and bipolar disorder is consistent with Swedish national epidemiological studies, which reported higher odds ratios in siblings for schizophrenia and bipolar disorder54 than for schizophrenia and ASD9. These results imply a modest overlap of common genetic etiological processes in these two disorders, consistent with emerging evidence from the discovery of copy number variants, in which both shared variants (for example, 15q13.3, 1q2.1 and 17q12 deletions56,57) and mutations in the same genes although with different variants (deletions associated with schizophrenia and duplications associated with autism and vice-versa10). The small ASD sample size thwarted attempts at further explorative partitioning of the SNP-based coheritability for schizophrenia and ASD.
