Overview of Lysosomal Storage Disorders
Lysosomal storage 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. Some hereditary metabolic disorders are X-linked, which means only one copy of the abnormal gene can cause the disorder in boys.
Lysosomes are tiny components within cells. Lysosomes contain enzymes that break down (metabolize) many types of molecules entering a cell. When the enzymes do not work correctly, the molecules build up, causing damage in many areas in the body.
Types of lysosomal storage disorders include
Mucopolysaccharidoses occur when the body lacks enzymes needed to break down and store complex sugar molecules (glycosaminoglycans).
Sphingolipidoses occur when people do not have the enzymes needed to break down sphingolipids, which are compounds that protect the cell surface and serve certain functions in the cells. There are many types of sphingolipidoses. The most common sphingolipidosis is
Others sphingolipidoses include
Niemann-Pick disease (types A and B)
Lipidoses occur when the body lacks one of the enzymes that help the body break down 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. Lipidoses include
Before birth, doctors diagnose some lysosomal storage disorders by doing the prenatal screening tests amniocentesis or chorionic villus sampling. After birth, some lysosomal storage disorders are diagnosed by routine newborn screening tests or other tests.
Treatment of lysosomal storage disorders varies depending on the substances that accumulate in the blood and tissues.