Thank you for donating!

You can donate using the following services.

ASMD Niemann-Pick Disease Type B

What is Niemann-Pick Disease Type B?

Niemann-Pick Disease Type A (NP-A) and Niemann-Pick Disease Type B (NP-B) were once thought to be separate diseases, but are now understood to be opposite ends of a spectrum of the same disease. They are both caused by a deficiency of the enzyme acid sphingomyelinase (ASM) and therefore are known as Acid Sphingomyelinase Deficiency (ASMD) Niemann-Pick disease. Many variations exist within this spectrum, in terms of clinical symptoms and rate of progression.

NP-B is a very rare inherited lysosomal storage disorder in which harmful quantities of a fatty substance called sphingomyelin build up in the body’s cells and organs.  In NP-B this build up mainly occurs in the liver, spleen and lungs. Unlike NP-A, NP-B does not affect the brain and, although growth may be slow, those affected will survive into adulthood with many being able to lead a full and active life. A small number of patients may be described as having A/B variant, falling in the middle of the spectrum and exhibiting neurological problems which may become more apparent over time.

It is inherited when two copies of a faulty gene (a mutation) are passed on to a child. In every pregnancy of a couple who each carry a copy of the faulty Niemann-Pick gene, there is a 1 in 4 chance (25%) that their child will have Niemann-Pick disease. This is known as autosomal recessive inheritance.

The incidence of NP-B is estimated as 1 in 250,000 in the general population.


Niemann-Pick Disease Type B (NP-B) is caused by a severe deficiency of the enzyme acid sphingomyelinase. This is required to break down a fatty substance called sphingomyelin.  Failure to break down sphingomyelin causes an accumulation and enlargement of the liver and spleen.


Niemann-Pick Disease Type B (NP-B) is diagnosed by measuring the level of the enzyme acid sphingomyelinase in the white blood cells. This can be done by testing a small blood sample.  The diagnosis is usually confirmed by DNA sequencing to identify mutations.

The enzyme deficiency at the cause of NP-B arises from mutations in a gene on chromosome 11.



The first symptoms of Niemann-Pick Disease Type B (NP-B) are usually an enlarged liver and/or spleen in early childhood.

Symptoms can include:

  • A progressive enlargement of organs
  • Poor growth
  • Susceptibility to respiratory infections
  • Bleeding problems
  • Bone pain
  • Increased stress on the heart

There is usually no neurological involvement in NP-B. Most patients will survive into adulthood, but not without experiencing health problems.


There is currently no specific approved treatment, or cure, for Niemann-Pick Disease Type B (NP-B). However, patients will benefit from palliative treatments (individual medications that will help to treat the symptoms related to the condition). These improve the quality of life of patients who are experiencing symptoms.

There are clinical trials currently taking place investigating new therapeutic options for patients with NP-B.

Video Overview

Latest news


"Time to Talk" (Virtual Elevenses - Webinar Series)

At this time of social distancing, it has never been more important to stay in touch. Being able to see each other’s faces and to reach out virtually to those we love and miss is essential. This virus may be isolating us but it is also uniting us – more than ever, we are in this together. We are vulnerable together, anxious together, sad together, scared together, and – most importantly - hopeful...

Read more


A message from Orphazyme to the global community of patients, family members and healthcare providers impacted by the corona virus pandemic (COVID-19):

In the days and weeks to come, Orphazyme will continue to communicate openly with patient organizations and clinical trial investigators around the globe to share the latest information regarding our efforts as the situation develops. Meanwhile please utilize attached FAQs to answer questions if any about our trials...

Read more
View all news Subscribe