Neimann-Pick Disease
· Symptoms
of Neimann-Pick Type A
· Symptoms
of Neimann-Pick Type B
· Diagnosis
· Treatment
· Incidence
in People of Jewish Descent
· Testing
· Resources
and More
There are four clinical types of Niemann-Pick Disease, all inherited.
Type A and Type B are caused by the lack of a substance called ASM-acid sphingomylinase
which breaks down a substance called sphingomyeline. Lack of ASM causes buildup
of sphingomyeline in certain cells and causes damage to the central nervous
system, liver, and lungs.
Though both Type A and B are caused by deficiency of ASM, Type A, which is most
prevalent, is a severe neurological disease that generally leads to death between
two and three years of age. Type B has little or no neurological involvement
and many survive into late childhood or adulthood.
Type C and D are also caused by excess deposition of sphingomyelin, as patients
do not properly transport sphingomyelin and that too results in its accumulation
of sphingomyeline. However, it is the A and B types of Neimann-Pick Disease
that have a higher incidence in Ashkenazi Jews, compared to the general population.
Symptoms
of Neimann-Pick Type A
The prognosis of Type A is dismal, and usually a baby with this form of Niemann-Pick
Disease succumbs by the second year of life. Symptoms and signs of Type A include:
· Abdominal distention
· Coordination and motor-skill difficulties
· Feeding problems
· Progressive spasticity
· Blindness
· Enlarged liver, and\or spleen
· A “ cherry red spot” in the eye,
visible by special eye exam.
· May also present with jaundice
in infancy and progressive liver failure.
Symptoms of Neimann-Pick Type
B
Neimann-Pick Type B is less extreme and does not affect the brain. However,
it does cause liver, spleen, lymph node, and bone marrow problems and generally
leads to abdominal distention and respiratory difficulties.
Diagnosis
Diagnosis is achieved by testing blood, and measuring the ASM activity in the
white blood cells. This test
is effective in identifying persons actually victims of Type A and B but is
not reliable in detecting persons who are carriers of Neimann-Pick.
Treatment
Currently Mount Sinai Hospital in New York in conjunction with Genzyme Corporation
is working on new treatment modes for Type B Neimann-Pick Disease. They will
be focusing on Enzyme Replacement Therapy and Gene Therapy.
Incidence in People of Jewish
Descent
One in 75 Ashkenazi Jews is a carrier.
The disease is transmitted through heredity. Both parents have to carry the
Neimann-Pick gene for there to be a possibility of transmission to their child.
If both parents are carriers then:
· There is a one in four chance that
the child will inherit the Neimann-Pick gene from each parent and have the disease
· There is a one in four chance that
the child will inherit normal genes from both parents and be completely free
of the disease.
· There is a two in four chance the
child will inherit one of each kind of gene and be a carrier like the parents,
and free of the disease.
· Unaffected siblings have a two
in three chance of being carriers.
Testing
There is a carrier screening test
which requires a sample of blood that can determine whether or not a gene change
is present in the gene for Neiman-Pick.
Prenatal diagnosis for Neimann-Pick can be attained with the use of CVS (Chorionic
Villus Smmpling) or Amniocentesis, which are performed early in the pregnancy.
Resources and More
National Neiman-Pick Disease Foundation, Inc.
3734 East Olive Avenue
Gilbert, AZ 85234
Telephone: 602-497-6638
Website:http://www.nnpdf.org