Figure 1. Cholesterol biosynthetic pathway (A) and its relationship to 5 human diseases that result from deficiencies of enzymes in the conversion of lanosterol to cholesterol (B).

For simplicity, the early steps from acetyl-CoA to HMG-CoA are not shown. The clinical features of the genetic diseases are reviewed in articles by Herman (4), Moebius et al. (47), and Porter (3). CHILD syndrome, congenital hemidysplasia with ichthyosiform erythroderma and limb defects; CDPX2 syndrome, X-linked dominant chondrodysplasia punctata type 2.