the basis of overlap with other syndromic neurodevelopmental disorders (e.g. Fragile X syndrome, Angelman syndrome, Rett syndrome), chromosomal abnormalities and copy number variation, and as causes for nonsyndromic autism (e.g. NRXN1, NLGN3/4X, SHANK3) [4], [10]. In a few cases, autism has been shown to be caused by homozygous recessive mutations due to recent shared ancestry [11], although the contribution of recessive mutations in outbred populations remains unexplored.
