Niemann-Pick diseaseSphingomyelinase deficiency
Niemann-Pick disease 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 4 most commonly recognized forms of the disease:
- Type A
- Type B
- Type C
- Type D
Types A and B are also known as type I, and types C and D are also known as type II.
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.
Niemann-Pick disease 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 D involves a defect that interferes with how cholesterol moves between brain cells. It is a variant of type C. This type has only been seen in French Canadian people in Yarmouth County, Nova Scotia.
Symptoms vary. Other health conditions may cause similar symptoms. The early stages of the disease may only cause a few symptoms. You 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 in the eye
- 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 patients may have repeated respiratory infections.
Type C usually affects school-age children. However, it may occur any time between early infancy to adulthood. Symptoms may include:
- Difficulty moving limbs
- Enlarged spleen
- Enlarged liver
- Jaundice at (or shortly after) birth
- Learning difficulties and intellectual decline
- Slurred, irregular speech
- Sudden loss of muscle tone which may lead to falls
- Trouble moving the eyes up and down
- Unsteady gait, clumsiness, walking problems
Symptoms of type D are similar to type C.
Exams and Tests
A blood or bone marrow test can be done to diagnose 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 the disease.
Other tests might include:
At this time, there is no effective treatment for type A.
Bone marrow transplants have been done on a few patients with type B with encouraging results. Researchers continue to study possible treatments, including enzyme replacement and gene therapy.
There is no specific treatment for type D. A new medicine called miglustat is available for the nervous system symptoms of type C.
A healthy, low-cholesterol diet is recommended. However, research does not show that these methods stop the disease from getting worse or change how cells break down cholesterol. However, medicines are available to control or relieve many symptoms, such as sudden loss of muscle tone and seizures.
For more information, visit the National Niemann-Pick Disease Foundation website: www.nnpdf.org
Type A Niemann-Pick is a severe disease. It usually leads to death by age 2 or 3.
Those with type B may live into late childhood or adulthood.
A child who shows signs of type C before age 1 may not live to school age. Those who show symptoms after entering school may live into their mid-to-late teens. Some may live into their 20s.
- Brain damage with intellectual disability and delayed development of physical skills
When to Contact a Medical Professional
Make an appointment with your health care provider if you have a family history of Niemann-Pick disease and you plan to have children. Genetic counseling and screening is recommended.
Call your health care provider if your child has symptoms of this disease, including:
- Developmental problems
- Feeding problems
- Poor weight gain
All types of Niemann-Pick are autosomal recessive. This means that both parents are carriers each carry 1 copy of the abnormal gene without having any signs of the disease themselves.
When both parents are carriers, there is a 25% chance that their child will have the disease and a 50% chance that their child will be a carrier.
Carrier detection testing is only possible if the genetic defect is identified. The defects involved in types A and B have been well-studied. DNA tests for these forms of Niemann-Pick are available.
Genetic defects have been identified in the DNA of many patients with type C. It may be possible to diagnose people who carry the abnormal gene.
A few centers offer tests to diagnose a baby still in the womb.
Krasnewich DM, Sidransky E. The lysosomal storage diseases. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 215.
Kwon JM. Neurodegenerative disorders of childhood. In: Kliegman RM, Stanton BF, St. Geme J, Schor N, Behrman RE, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 592.
NP-C Guidelines Working Group, Wraith JE, Baumgartner MR, Bembi B, et al. Recommendations on the diagnosis and management of Niemann-Pick disease type C. Mol Genet Metab. 2009;98:152-65. PMID: 19647672 www.ncbi.nlm.nih.gov/pubmed/19647672.
Review Date: 11/25/2014
Reviewed By: Chad Haldeman-Englert, MD, FACMG, Wake Forest School of Medicine, Department of Pediatrics, Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.