DHCR7 and Peroxisome biogenesis disorder-Zellweger syndrome spectrum: For example, Smith–Lemli–Optiz syndrome, Peroxisome biogenesis disorder, Greenberg dysplasia, and Conradi–Hunermann syndromes are linked to mutations in genes coding for enzymes (7-dehydrocholesterol reductase—DHCR7, acyl-CoA oxidase 1-ACOX1, 3 b-Hydroxysteroid 8, 7-sterol isomerase) involved in the synthesis of cholesterol, and all four commonly lead to reduced myelin formation that clinically manifests itself in developmental delay, motor dysfunction, and more (for further details, specific references are indicated in the table).