Disease Overview
The National Niemann-Pick Disease Foundation (NNPDF) does not engage in the practice of medicine. It is not a medical authority nor does it claim to have medical knowledge. This site is an educational service of the National Niemann-Pick Disease Foundation and is not meant to provide diagnostic or treatment advice. Information contained or suggested on this Web site does not constitute medical advice. For all information related to care, medication or treatment, the NNPDF recommends consulting a physician to determine if information presented is applicable. Please review these additional cautions about medical information provided on the Internet.
Niemann-Pick Disease is one of a group of lysosome storage diseases that
affect metabolism and that are caused by genetic mutations.
The three most commonly recognized forms are Niemann-Pick
Types A, B and C.
[One child's struggle with the progression of Niemann-Pick
Disease]
Niemann-Pick Types A and B (NPA and NPB)
are caused by the deficiency of a specific enzyme, acid sphingomyelinase
(ASM). This enzyme is found in special compartments within
cells called lysosomes and is required to metabolize a lipid
called sphingomyelin. If ASM is absent or not functioning
properly, sphingomyelin cannot be metabolized properly and
is accumulated within the cell, eventually causing cell death
and the malfunction of major organ systems.
NPA and NPB are both caused by the same
enzymatic deficiency and there is a growing evidence that
the two forms represent opposite ends of a continuum. People
with NPA generally have little or no ASM production (less
than 1% of normal) while those with NPB have approximately
10% of the normal level of ASM.
The clinical prognosis for NPA and NPB patients
is very different. NPA is a severe neurologic disease that
leads to death by 2 to 4 years of age. In contrast,
patients with NPB generally have little or no neurologic involvement
and may survive into late childhood or adulthood. Type B individuals
usually have enlarged livers and spleens, and respiratory
problems are common. The enlargement of organs and the respiratory
problems can cause cardiovascular stress and can lead
to heart disease later in life.
There are approximately 1,200 cases of NPA
and NPB world wide with the majority being Type B or an intermediate
form.
Mayo Clinic podcast featuring Dr. Marc Patterson in a discussion about Niemann-Pick Disease Type C. (7/15/2008)
Niemann-Pick Type C (NPC) is very different
than Type A or B. NPC Patients are not able to metabolize
cholesterol and other lipids properly within the cell. Consequently,
excessive amounts of cholesterol accumulate within the liver
and spleen and excessive amounts of other lipids accumulate
in the brain. NPC causes a secondary reduction of ASM activity,
which led all three types to be considered forms of the same
disease.
There is considerable variation in when
Type C symptoms first appear and in the progression of the
disease. Symptoms may appear as early as a few months of age
or as late as adulthood. Vertical gaze palsy (the inability
to move the eyes up and down), enlarged liver, enlarged spleen,
or jaundice in young children are strong indications that
NPC should be considered. It is common for only one or two
symptoms to appear in the early stages of the disease.
In most cases, neurological symptoms begin
appearing between the ages of 4 and 10. Generally, the
later neurological symptoms begin, the slower the progression
of the disease.
Type C Niemann-Pick Disease has about 500
cases diagnosed worldwide. It is believe, however, that
the number of people affected by NPC is higher, but diagnostic
difficulties do not allow an accurate assessment of the occurrence
rate. NPC has been initially diagnosed as a learning
disability, mild retardation, "clumsiness," and
delayed development of fine motor skills. It is not uncommon
for a family to spend several years seeking a diagnosis before
NPC is identified.
NPC is always fatal. The vast majority of
children die before age 20 (and many die before the age of
10). Late onset of symptoms can lead to longer life spans
but it is extremely rare for any person with NPC to reach
age 40.
Niemann-Pick Disease
affects all segments of the population with cases reported
from North America, South America, Europe, Africa, Asia, and
Australia. However a higher incidence has been found in
certain populations:
Ashkenazi Jewish population (NPA and NPB)
French Canadian population of Nova Scotia
(type D – now considered a variant of NPC)
Maghreb region (Tunisia, Morocco, and Algeria)
of North Africa (NPB)
Spanish-American population of southern
New Mexico and Colorado (NPC)
Links and other NPD Resources
Other NPD organizations
Organizations addressing other lysosome storage diseases
Pick's
Disease is sometimes confused with Niemann-Pick Disease
but it is a different disease.
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