Smith-Lemli-Opitz syndrome (SLOS; OMIM 270400) is an autosomal recessive, multiple malformation, neurodevelopmental disorder caused by pathological variants of 7-dehydrocholesterol reductase (DHCR7), a terminal enzyme in cholesterol biosynthesis (2). The gene discussed is DHCR7; the disease is Smith-Lemli-Opitz syndrome.