Niemann-Pick Disease

Diagnosis of Niemann-Pick disease begins with a physical exam. The exam may show an early warning sign such as a liver or spleen that is too large. Your healthcare professional talks with you about symptoms and your family health history. Niemann-Pick disease is rare, and its symptoms can be similar to those of other health conditions, so testing is needed to get the right diagnosis.

Diagnostic tests depend on the type of Niemann-Pick disease.

• Type A or B. Using blood or a tiny sample of skin, experts measure how much sphingomyelinase is in white blood cells. Sphingomyelinase is an enzyme that breaks down and uses fat.
• Type C. Experts use a blood sample to measure levels of a specific type of cholesterol called oxysterol. In rare cases, a small sample of skin also can be used to tell how the cells move and store cholesterol.

Other tests also may be done, such as:

• Genetic testing. DNA testing of a blood sample may show the specific gene changes that cause Niemann-Pick disease types A, B and C. People who have only one copy of the gene change but do not have the condition are called carriers. DNA tests can show carriers for all types of Niemann-Pick disease if the gene changes have been identified in the first person in a family to have the condition. The gene change can be passed on to children.
• Magnetic resonance imaging (MRI). An MRI of the brain may show loss of brain cells. But in the early stages of Niemann-Pick disease, an MRI may not show any changes because symptoms usually show up before the loss of brain cells. MRI also can be used to look at the liver and spleen to see if they are large and to measure their size.
• Eye exam. An eye exam may show changes that could be caused by Niemann-Pick disease, such as problems with eye movements in type C and changes inside the eyes in types A and B.
• Prenatal testing. Ultrasound during pregnancy can show the large liver and spleen caused by Niemann-Pick disease type C. The liver and spleen also may be large in type A, but rarely in type B. Taking a sample of amniotic fluid from around the baby in the womb or taking a sample of tissue from the placenta may be done to diagnose Niemann-Pick disease.

Genetic testing and counseling for families with a child with Niemann-Pick disease can give information about risks and family planning options.