Niemann-Pick disease is type of lysosomal storage disorder. Types A and B are sphingolipidoses and are caused by a buildup of sphingomyelin in the tissues. Type C is a lipidosis that is caused by a build up of cholesterol and other fats (lipids) in the cells. This disease causes many neurologic problems. Niemann-Pick disease occurs when parents pass on to their children the defective genes that cause this disease.
Niemann-Pick disease types A and B occur when the body lacks enzymes needed to break down sphingomyelin.
Niemann-Pick disease type C occurs when the body is not able to break down cholesterol and other lipids.
Symptoms vary by type but may include intellectual disability and neurologic problems.
The diagnosis is based on blood tests.
Niemann-Pick disease cannot be cured.
There are different types of inherited disorders. In Niemann-Pick disease, both parents of the affected child carry 1 copy of the abnormal gene. Because usually 2 copies of the abnormal (recessive) gene are necessary for the disorder to occur, usually neither parent has the disorder. (See also Overview of Hereditary Metabolic Disorders.)
Sphingolipidoses occur when people do not have the enzymes needed to break down (metabolize) sphingolipids, which are compounds that protect the cell surface and serve certain functions in the cells. There are many types of sphingolipidoses besides Niemann-Pick disease types A and B.
Types of Niemann-Pick Disease
Niemann-Pick disease has several types. In types A and B, the deficiency of a specific enzyme called sphingomyelinase results in the accumulation of sphingomyelin (a product of fat metabolism). In type C, there is a defect in how fats (lipids) are moved around in a cell, resulting in accumulation of cholesterol and other fatty substances.
The most severe types tend to occur in people of Ashkenazi Jewish ancestry. The milder forms occur in all ethnic groups.
Children with type A (the most severe form) fail to grow normally and have several neurologic problems. These children usually die by age 2 or 3.
Children with type B develop fatty growths in the skin, areas of dark pigmentation, and an enlarged liver, spleen, and lymph nodes. They may be intellectually disabled.
Children with type C develop symptoms usually during childhood, with seizures and neurologic deterioration. Type C is always fatal, and most children die before age 20.
Diagnosis of Niemann-Pick Disease
Prenatal screening tests
Newborn screening tests
Blood and sometimes DNA tests
Before birth, Niemann-Pick disease types A and B can be diagnosed in the fetus by using the prenatal screening tests chorionic villus sampling or amniocentesis.
After birth, the diagnosis of Niemann-Pick disease types A and B may be diagnosed in some states in the United States by routine newborn screening tests. Newborn screening tests cannot be done for type C.
Doctors also measure levels of sphingomyelinase in white blood cells for types A and B. 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 for all 3 types.
Tests of DNA (the building blocks of genes) may be done to identify carriers. Carriers are people who have an abnormal gene for a disorder but who do not have symptoms or visible evidence of the disorder.
Treatment of Niemann-Pick Disease
Possible bone marrow transplantation, stem cell transplantation, and enzyme replacement
None of the types of Niemann-Pick disease can be cured, and children tend to die of infection or progressive dysfunction of the central nervous system (the brain and spinal cord).
Currently, some therapies that may slow or halt the progression of symptoms, such as bone marrow transplantation, stem cell transplantation, and enzyme replacement, are being studied.
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
Jewish Genetic Disease Consortium (JGDC): A resource for people of Jewish ancestry who want to undergo carrier screening for certain genetic diseases
National Organization for Rare Disorders (NORD): This resource provides information to parents and families about rare diseases, including a list of rare diseases, support groups, and clinical trial resources.
Genetic and Rare Diseases Information Center (GARD): This resource provides and easy to understand information about rare or genetic diseases.
