DHCR7 and Smith-Lemli-Opitz syndrome: For instance, mutations in DHCR7 within the Kandutsh-Russell pathway (Figure 1) result in Smith-Lemli-Opitz syndrome (SLOS), a disease characterized by low cholesterol levels in the brain that primarily cause intellectual disabilities, psychiatric problems and delayed maturation of both motor and language skills (Segatto et al., 2014).