Inborn errors of sterol biosynthesis

The known disorders of cholesterol biosynthesis have expanded rapidly since the discovery that Smith-Lemli-Opitz syndrome is caused by a deficiency of 7-dehydrocholesterol. Each of the six now recognized sterol disorders-meva lonic aciduria, Smith-Lemli-Opitz syndrome, desmosterolosis, Conradi-Hunerm ann syndrome, CHILD syndrome, and Greenberg dysplasia-has added to our know ledge of the relationship between cholesterol metabolism and embryogenesis. One of the most important lessons learned from the study of these disorder s is that abnormal cholesterol metabolism impairs the function of the hedge hog class of embryonic signaling proteins, which help execute the vertebrat e body plan during the earliest weeks of gestation. The study of the enzyme s and genes in these several syndromes has also expanded and better delinea ted an important class of enzymes and proteins with diverse structural func tions and metabolic actions that include sterol biosynthesis, nuclear trans criptional signaling, regulation of meiosis, and even behavioral modulation .