Overview Of Niemann-Pick Disease (NPD)
Niemann-Pick Disease (NPD) is a group of diseases passed down through families (inherited) in which fatty substances called lipids collect in the cells of the spleen, liver, and brain.
There are three common forms of the disease:
- Type A
- Type B
- Type C
Each type involves different organs. It may or may not involve the nervous system and breathing. Each one can cause different symptoms and may occur at different times throughout life.
Commonly Associated With
Sphingomyelinase deficiency; Lipid storage disorder – Niemann-Pick disease; Lysosomal storage disease – Niemann-Pick
Causes Of Niemann-Pick Disease (NPD)
NPD types A and B occur when cells in the body do not have an enzyme called acid sphingomyelinase (ASM). This substance helps break down (metabolize) a fatty substance called sphingomyelin, which is found in every cell in the body.
If ASM is missing or does not work properly, sphingomyelin builds up inside cells. This kills your cells and makes it hard for organs to work properly.
Type A occurs in all races and ethnicities. It is more common in the Ashkenazi (Eastern European) Jewish population.
Type C occurs when the body cannot properly break down cholesterol and other fats (lipids). This leads to too much cholesterol in the liver and spleen and too much of other lipids in the brain. Type C is most common among Puerto Ricans of Spanish descent.
Type C1 is a variant of type C. It involves a defect that interferes with how cholesterol moves between brain cells. This type has only been seen in French Canadian people in Yarmouth County, Nova Scotia.
Symptoms Of Niemann-Pick Disease (NPD)
Symptoms vary. Other health conditions may cause similar symptoms. The early stages of the disease may only cause a few symptoms. A person may never have all symptoms.
Type A usually begins in the first few months of life. Symptoms may include:
- Abdominal (belly area) swelling within 3 to 6 months
- Cherry red spot at the back of the eye (on the retina)
- Feeding difficulties
- Loss of early motor skills (gets worse over time)
- Type B symptoms are usually milder. They occur in late childhood or the teenage years. Abdominal swelling may occur in young children. There is almost no brain and nervous system involvement, such as loss of motor skills. Some children may have repeated respiratory infections.
Types C and C1 usually affect school-age children. However, it may occur any time between early infancy to adulthood.
Symptoms of NPD may include:
- Difficulty moving limbs that may lead to unsteady gait, clumsiness, walking problems
- Enlarged spleen
- Enlarged liver
- Jaundice at (or shortly after) birth
- Learning difficulties and intellectual decline
- Slurred, irregular speech
- Sudden loss of muscle tone that may lead to falls
- Trouble moving the eyes up and down
Exams & Tests
A blood or bone marrow test can be done to diagnose niemann-pick disease types A and B. The test can tell who has the disease but does not show if you are a carrier. DNA tests can be done to diagnose carriers of types A and B.
A skin biopsy is usually done to diagnose types C and D. The health care provider watches how the skin cells grow, move, and store cholesterol. DNA tests may also be done to look for the 2 genes that cause this type of disease.
Other tests might include:
- Bone marrow aspiration
- Liver biopsy (usually not needed)
- Slit-lamp eye exam
- Tests to check the level of ASM
Treatment Of Niemann-Pick Disease (NPD)
At this time, there is no effective treatment for type A.
Bone marrow transplants may be tried for type B. Researchers continue to study possible treatments, including enzyme replacement and gene therapy.
A new medicine called miglustat is available for the nervous system symptoms of type C.
High cholesterol may be managed with a healthy, low-cholesterol diet or medicines. However, research does not show that these methods stop the disease from getting worse or change how cells break down cholesterol. Medicines are available to control or relieve many symptoms, such as sudden loss of muscle tone and seizures.