What are the genetic changes related to congenital hemidysplasia with ichthyosiform erythroderma and limb defects ?
Mutations in the NSDHL gene cause CHILD syndrome. This gene provides instructions for making an enzyme that is involved in the production of cholesterol. Cholesterol is a type of fat that is produced in the body and obtained from foods that come from animals, particularly egg yolks, meat, fish, and dairy products. Although high cholesterol levels are a well-known risk factor for heart disease, the body needs some cholesterol to develop and function normally both before and after birth. Cholesterol is an important component of cell membranes and the protective substance covering nerve cells (myelin). Additionally, cholesterol plays a role in the production of certain hormones and digestive acids.  The mutations that underlie CHILD syndrome eliminate the activity of the NSDHL enzyme, which disrupts the normal production of cholesterol within cells. A shortage of this enzyme may also allow potentially toxic byproducts of cholesterol production to build up in the body's tissues. Researchers suspect that low cholesterol levels and/or an accumulation of other substances disrupt the growth and development of many parts of the body. It is not known, however, how a disturbance in cholesterol production leads to the specific features of CHILD syndrome.