Other Rare Hereditary Disorders of Lipid Metabolism
Lipid metabolism disorders are hereditary metabolic disorders. Hereditary disorders occur when parents pass the defective genes that cause these disorders on to their children. There are different types of inherited disorders. In many hereditary metabolic disorders, both parents of the affected child carry a copy of the abnormal gene. Because usually two copies of the abnormal gene are necessary for the disorder to occur, usually neither parent has the disorder.
Lipids are fats, which are an important source of energy for the body. The body’s store of fat is constantly broken down and reassembled to balance the body’s energy needs with the food available. Groups of specific enzymes help the body break down (metabolize) and process fats. Certain abnormalities in these enzymes can lead to the buildup of specific fatty substances that normally would have been broken down by the enzymes. Over time, accumulations of these substances can be harmful to many organs of the body. Lipidoses are disorders caused by the accumulation of lipids.
The accumulation of fatty substances can cause disorders such as
Other enzyme abnormalities prevent the body from converting fats into energy normally. These abnormalities are called fatty acid oxidation disorders.
Many lysosomal storage disorders also involve problems with lipid metabolism.
Before birth, doctors diagnose some lipid metabolism disorders by doing the prenatal screening tests amniocentesis or chorionic villus sampling. After birth, some lipid metabolism disorders are diagnosed by routine newborn screening tests or other tests.
Treatment of lipid metabolism disorders varies depending on the type of fatty substances that accumulate in the blood and tissues.
This disorder occurs when cholestanol, a product of cholesterol metabolism, accumulates in tissues. This disease eventually leads to uncoordinated movements, dementia, cataracts, early coronary artery disease, and fatty growths (xanthomas) on tendons. The disabling symptoms often appear after age 30.
If started early, the drug chenodiol (chenodeoxycholic acid) helps prevent progression of the disease, but it cannot undo any damage already done. People may also given statins because these drugs lower lipid levels in the blood.
In this disorder, fats from fruits and vegetables accumulate in blood and tissues. The buildup of fats leads to atherosclerosis, early coronary artery disease, abnormal red blood cells, and xanthomas on tendons.
Treatment of sitosterolemia consists of reducing the intake of foods that are rich in plant fats, such as vegetable oils, and taking cholestyramine resin. Doctors may also give the drug ezetimibe, which reduces the amount of cholesterol absorbed by the body.