Modified figure of the paper by Krumm and collaborators. A comparison of the effect size of different genetic risk factors in autism, comparing affected and unaffected siblings. In summary, in affected siblings, there is an enrichment of de novo mutations, large copy number variants, and inherited small copy number variants. When the risk between these different classes of genetic variants is compared, small inherited CNVs represent a minor, but independent, genetic risk factor, a novel type of genetic morbidity in neurodevelopmental disease. (non-copyrighted version of figure provided by author, SNV – single nucleotide variations, CNV copy number variations)