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. Some hereditary metabolic disorders are X-linked, which means only one copy of the abnormal gene can cause the disorder in boys. (See also Overview of Hereditary Metabolic Disorders.)
Lipidoses occur when the body lacks one of the enzymes that help the body break down (metabolize) and process fats (lipids). This 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.
In cholesteryl ester storage disease and Wolman disease, cholesterol and triglycerides, which are important fats in the blood, accumulate in tissues. The enzyme needed to break down cholesterol and triglycerides, called lysosomal acid lipase, does not work correctly.
Wolman disease is the more severe disease. This disease occurs in the first few weeks of life. Infants feed poorly, vomit, and have an enlarged spleen and liver. Calcium deposits in the adrenal glands cause them to harden. Bowel movements contain excess fat, which results in oily, unusually foul-smelling, bulky stools (steatorrhea). Infants with Wolman disease usually die by 6 months of age if untreated.
Cholesteryl ester storage disease is less severe than Wolman disease and may not occur until later in life, even adulthood, at which time people may have an enlarged liver and spleen. People may develop premature hardening of the arteries (atherosclerosis), which is often severe.
Before birth, cholesteryl ester storage disease and Wolman disease can be diagnosed in the fetus by chorionic villus sampling.
After birth, doctors measure levels of lysosomal acid lipase in a biopsy sample of the liver or other tissues (removal of a tissue specimen for examination).
Genetic testing, which is used to determine whether a couple is at increased risk of having a baby with a hereditary genetic disorder, is also available.