Niemann-Pick disease (NP)

The clinical picture of Niemann-Pick disease was first recognised and described by Albert Niemann and Ludwig Pick, hence the name.

Niemann-Pick disease is also known as NP.

NP is characterised as an autosomal recessive lysosomal storage disorder caused by a genetic deficiency of acid sphingomyelinase. The main feature is the disturbed storage of certain lipids, especially sphingomyelin and cholesterol.

Worldwide, the NP-A and NP-B forms are rare, with a frequency of about 1:250,000 newborns. Surprisingly, the neuropathic type NP-A is most common among Ashkenazi Jews, with a rate of almost 1:100.

NP can be divided into different types:

• NP Type A and B
• NP Type C (Further divided into C1 and C2)
  

Genetic mutations, specifically in the SMPD1 gene, lead to a deficiency of acid sphingomyelinase, which mainly causes NP-A and NP-B. NP-C, on the other hand, results from defects in the NPC1 and NPC2 genes, with NPC1 being more commonly affected.

• Yellowish papules: Some patients with Niemann-Pick disease type B may develop small, raised, yellowish papules (nodules) on the skin, especially in the skin folds, on the hands, elbows and knees. These papules are due to the accumulation of sphingomyelin in the cells of the skin.
• Icterus (yellowing of the skin): Some newborns with Niemann-Pick disease type A may show icterus, but this can also be seen in many healthy newborns.
• Discolouration of the skin: Sometimes patients with Niemann-Pick disease may show bluish patches on the skin.
• Sufferers often show systemic signs such as an enlarged liver and spleen (hepatosplenomegaly), neurological problems and, depending on the type, specific features such as reddish spots on the retina or lung problems.

The identification of NP-A and NP-B is done by genetic testing and the detection of an enzyme deficiency in blood cells. For NP-C, genetic tests of the NPC1 or NPC2 genes provide the evidence. Also known as sphingomyelin cholesterol lipidosis, NP has various neurological disorders and shares similarities with diseases such as Fabry disease and Krabbe disease. It is essential to differentiate between these diseases and to make an accurate diagnosis. Treatment is currently focused on symptom relief and improving quality of life.

Treatment is currently focused on symptom relief and improving quality of life

The disease affects diverse systems, including the central nervous system, liver, spleen and, in some cases, the lungs.

Affected individuals often show symptoms in childhood, especially with NP-A. With other types, however, these may only appear in adulthood and less noticeably.

A characteristic feature in NP-A are the so-called cherry-red spots in the macula of the eye.

Other consequences include lung disease, cirrhosis of the liver, problems with the spleen and neurological degradation.

While NP-A patients usually only reach an age of 2 years, NP-B sufferers can lead a normal life into adulthood. In NP-C, the course varies greatly.

To date, there is no prevention strategy, as it is a genetic disorder.

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