Diagnosis guide
Niemann-Pick disease
If you or someone you love has just heard this diagnosis, start here. It covers several subtypes, and this guide shows how they differ, so you can find the one on your report.
Niemann-Pick disease is a name for rare inherited conditions in which fats build up inside cells. It is divided into four main types, A, B, C1 and C2, but these are really two different diseases with different causes. Types A and B, and an in-between form called A/B, are now called acid sphingomyelinase deficiency (ASMD). A missing enzyme lets a fat called sphingomyelin build up in the liver, spleen and lungs and, in type A and to a lesser degree type A/B, the brain. Types C1 and C2 make up Niemann-Pick type C. Cells cannot move cholesterol and other fats, and the disease slowly damages the brain and nerves. The two groups have different treatments. Donor stem cell transplants have been tried for ASMD. They helped the liver, spleen and blood counts but did not protect the brain, and their risks limit their use. Transplant is rarely used for ASMD today, and the 2025 international guidelines for type C do not include it.
In short
- Niemann-Pick disease is a name for rare inherited conditions in which fats build up inside cells. Types A and B are now called ASMD, and types C1 and C2 make up Niemann-Pick type C.
- An enzyme medicine, olipudase alfa, treats the problems of ASMD outside the brain. For type C, medicines approved in the US in 2024 treat brain and nerve symptoms.
- Donor transplants have been tried for ASMD, but they did not protect the brain. Transplant is rarely used today, and the 2025 guidelines for type C do not include it.
Find the subtype on your report
The exact diagnosis shapes the treatment options. Your care team can explain the name on your report.
Acid sphingomyelinase deficiency (types A, A/B and B) 1 subtype
An enzyme disorder that mainly affects the liver, spleen and lungs, and in type A also the brain.
Niemann-Pick type C 2 subtypes
A disorder of fat and cholesterol transport that slowly affects the brain and nerves.
Niemann-Pick disease type C1 (NPC1)
Niemann-Pick disease type C1 is the NPC1 gene form of Niemann-Pick type C, a rare inherited lysosomal disorder in which cells cannot move cholesterol and other fats. It slowly damages the brain and nerves and can affect the liver, spleen and lungs.
Not treated with transplantNiemann-Pick disease type C2 (NPC2)
NPC2-related Niemann-Pick disease type C is a genetic disorder of intracellular lipid transport. It can affect the liver, spleen, lungs and nervous system; some infants have severe pulmonary disease.
Limited transplant role
Related diagnosis guides
Key facts
- Two different diseases
- Types A and B (ASMD) come from the SMPD1 gene; types C1 and C2 from the NPC1 or NPC2 geneMedlinePlus Genetics (last updated January 2015). Source: Two different diseases
- Type C: how common
- About 1 in 100,000 live births; at least 95 in 100 cases are NPC1Estimated incidence per live births; type C occurs in all ethnic groups. 2025 international consensus guidelines for Niemann-Pick type C (Journal of Inherited Metabolic Disease, 2026). Source: Type C: how common
- ASMD enzyme therapy
- Olipudase alfa (Xenpozyme), authorised in the EU in June 2022 for types A/B and BEuropean Union, European Medicines Agency. It treats problems outside the brain. Source: ASMD enzyme therapy
- Type C medicines
- Two approved in the U.S. within a week in September 2024U.S. Food and Drug Administration, September 2024: arimoclomol (with miglustat) and levacetylleucine, for neurological symptoms. Source: Type C medicines
How Niemann-Pick disease is diagnosed
In ASMD type A, a baby usually has a large liver and spleen by about 3 months of age. Types A/B and B can appear from childhood to adulthood with a large spleen and liver, lung problems or low platelets. Niemann-Pick type C most often shows up in childhood with trouble with coordination (ataxia), difficulty moving the eyes up and down and a slow decline in thinking skills. It can begin at any age, and in babies it can start with jaundice and a large liver and spleen.
For ASMD, the key test measures the acid sphingomyelinase enzyme in white blood cells or a dried blood spot. International guidelines say a dried blood spot result is confirmed with a white blood cell test or a genetic test. The genetic test looks for changes in both copies of the SMPD1 gene. A blood marker called lyso-sphingomyelin is strongly raised in ASMD.
Type C is found a different way. The 2025 international guidelines recommend blood tests for biomarkers first, such as oxysterols, followed by genetic testing of the NPC1 and NPC2 genes to confirm it. Referral to a clinical geneticist or genetic counselor is suggested after diagnosis.
A large spleen has many possible causes, so adults with ASMD sometimes have a bone marrow biopsy to look for cancer. The ASMD guidelines say this is not needed for the diagnosis. Because ASMD, Gaucher disease and type C can look alike, the ASMD guidelines advise that testing for Gaucher disease or type C should also include ASMD. For type C, GeneReviews advises checking brothers and sisters early, so that any who might benefit from treatment are found.
Looking ahead
Outlook for Niemann-Pick disease
The outlook depends on the type. International ASMD guidelines say type A usually leads to death by about age 3. People with types A/B and B can live into adulthood, even without treatment. In type B, liver failure is one of the leading causes of death, and some people develop serious lung disease.
Olipudase alfa treats the problems of ASMD outside the brain. GeneReviews notes that as more people are treated for longer, the usual course of ASMD is likely to change. The medicine does not treat the brain, so it does not change the brain disease of type A.
Niemann-Pick type C usually gets worse slowly. When it begins in mid- to late childhood, death, usually from pneumonia caused by food or liquid entering the lungs (aspiration), tends to come in the late teens or 20s. When it begins in the teens or adulthood, it moves much more slowly. Medicines approved in the U.S. in 2024 treat the brain and nerve symptoms, but GeneReviews says no cure exists.
These descriptions come from reviews of small groups of people, many of them untreated. They cannot predict how any one person will do.
Common questions
What are the types of Niemann-Pick disease?
MedlinePlus Genetics describes four main types: A, B, C1 and C2. Types A and B come from changes in the SMPD1 gene. GeneReviews now calls them acid sphingomyelinase deficiency (ASMD), with an in-between form called type A/B. Types C1 and C2 come from changes in the NPC1 or NPC2 gene. Their signs are very similar, and they differ only in their genetic cause. Type C1 is far more common.
Is Niemann-Pick type C the same disease as types A and B?
No. They share a name, but they have different genes and different treatments. In ASMD (types A and B), an enzyme that breaks down a fat called sphingomyelin is missing. In type C, cells cannot move cholesterol and other fats to where they belong. Type C mainly causes slowly worsening problems with movement, eye movements, swallowing and thinking.
Can a bone marrow transplant treat Niemann-Pick disease?
Rarely, and not for the brain. For ASMD, GeneReviews says a donor stem cell transplant can correct the enzyme problem, improve blood counts and shrink the liver and spleen, but it does not stabilize brain disease. International ASMD guidelines say its risks, such as graft-versus-host disease and infection, limit its use. GeneReviews adds that it is likely to become obsolete now that enzyme therapy exists. The 2025 international guidelines for type C do not include transplant among its treatments.
Is there a treatment for Niemann-Pick disease?
Yes, for some forms. For ASMD, olipudase alfa (Xenpozyme) is an enzyme given by vein every two weeks. It was approved in the U.S. in August 2022 for problems outside the brain, and in the European Union in June 2022 for types A/B and B. For type C, the U.S. approved arimoclomol (Miplyffa), taken with miglustat, in September 2024, followed a few days later by levacetylleucine (Aqneursa). Both treat neurological symptoms. The European Union authorized levacetylleucine in January 2026. Miglustat alone is approved in several countries but not by the FDA for type C.
How common is Niemann-Pick disease?
All types are rare. MedlinePlus Genetics estimates that types A and B affect about 1 in 250,000 people, and type A is more common in people of Ashkenazi Jewish descent. The 2025 international guidelines estimate type C at about 1 in 100,000 live births, with at least 95 in 100 cases caused by NPC1. Experts think milder forms of both ASMD and type C are underdiagnosed.
What is the life expectancy with Niemann-Pick disease?
It depends on the type. Children with type A generally do not survive past early childhood. People with type B usually survive into adulthood. For type C, GeneReviews says death usually comes in the late teens or 20s when symptoms begin in childhood, and later-onset forms move more slowly. GeneReviews expects enzyme therapy to change the usual course of ASMD over time. The outlook section on this page explains more, and no description can predict one person’s course.
Is Niemann-Pick disease inherited?
Yes. All types are autosomal recessive: a person has the disease when both copies of the gene are changed. Parents usually each carry one changed copy and have no symptoms. When both parents are carriers, each child has a 1 in 4 chance of having the disease. Once the family’s gene changes are known, relatives can have carrier testing, and testing during or before pregnancy is possible.
Niemann-Pick disease
From the Jada Bascom Foundation disease library, jadabascomfoundation.org. Printed .
Questions to bring to your care team
- Is this ASMD (type A, A/B or B) or Niemann-Pick type C, and which gene changes were found?
- Is olipudase alfa (Xenpozyme) available to us, and which problems would it help?
- For type C, which medicines can we get here, and how will you track the brain and nerves over time?
- Should brothers and sisters be tested now, even if they seem well?
- What is the goal of each treatment you are suggesting?
- What would make a transplant worth considering later on?
- Are there clinical trials that might fit?
- Where can our family find support during treatment?
A one-page list to take to the next appointment, with room for notes.
Supporting someone with a diagnosisSupport for patients and families
These independent organizations offer information and support. JBF is not affiliated with them.
- National Niemann-Pick Disease Foundation US nonprofit supporting families affected by ASMD and Niemann-Pick type C, with family assistance, ASMD and NPC care clinics, a family conference and advocacy.United States
- Niemann-Pick UK UK charity offering care and support services, including financial help and bereavement support, to people and families affected by ASMD and Niemann-Pick type C.United Kingdom
- International Niemann-Pick Disease Alliance A global network of nonprofit groups supporting people affected by Niemann-Pick diseases, with an international patient registry.Worldwide
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Short explainers on what a transplant is and what it means for a family.
Sources and further reading
- Niemann-Pick disease
MedlinePlus Genetics, U.S. National Library of Medicine, Last updated 2015-01-01; accessed 2026-09-26 - Acid Sphingomyelinase Deficiency
GeneReviews, University of Washington / NCBI Bookshelf, Revised 2023-04-27; accessed 2026-09-26 - Niemann-Pick Disease Type C
GeneReviews, University of Washington / NCBI Bookshelf, Revised 2025-11-20; accessed 2026-09-26 - Consensus clinical management guidelines for acid sphingomyelinase deficiency (Niemann–Pick disease types A, B and A/B)
Orphanet Journal of Rare Diseases (Geberhiwot T, et al.), 2023-04-17; accessed 2026-09-26 - 2025 Consensus Clinical Management Guidelines for Niemann-Pick Disease Type C
Journal of Inherited Metabolic Disease (Hiwot T, et al.), 2026-05-01; accessed 2026-09-26 - Xenpozyme (olipudase alfa): EPAR medicine overview
European Medicines Agency, EU authorisation 2022-06-24; accessed 2026-09-26 - Drug Trials Snapshots: XENPOZYME
U.S. Food and Drug Administration, Approval date 2022-08-31; accessed 2026-09-26 - FDA Approves First Treatment for Niemann-Pick Disease, Type C
U.S. Food and Drug Administration, 2024-09-20; accessed 2026-09-26 - FDA Approves New Drug to Treat Niemann-Pick Disease, Type C
U.S. Food and Drug Administration, 2024-09-24; accessed 2026-09-26 - Aqneursa (levacetylleucine): EPAR
European Medicines Agency, Accessed 2026-09-26
