This model is in contrast to that reported for syndromic CNVs, where the core phenotypes can be due to a single gene (such as RAI1 in Smith-Magenis syndrome) or a subset of individual genes in the contiguous region (as in Williams syndrome), but agrees with previous findings showing synergistic interactions between genes within de novo CNVs identified in individuals with autism25. This evidence concerns the gene RAI1 and Smith-Magenis syndrome.