DHCR7 and Smith-Lemli-Opitz syndrome: The Smith-Lemli-Opitz Syndrome (SLOS), a genetic condition of impaired cholesterol biosynthesis due to mutations of the 7-dehydrocholesterol reductase gene (DHCR7), has been found to be associated with autism, supporting genetic defects in cholesterol metabolism can cause autism (Sikora et al., 2006; Bukelis et al., 2007; Diaz-Stransky and Tierney, 2012).