Niemann-Pick neurological disorders). This accumulation can be caused by

Niemann-Pick disease (NP) is an
autosomal recessive disorder that is typically classified into four main categories
based on the genetic cause and symptoms: type A, type B, type C1, and type C2. NP
is a lipid storage disease meaning that “harmful quantities of lipids
accumulate in the brain, spleen, liver, lungs, and bone marrow” (National institute
of neurological disorders). This accumulation can be caused by a mutation to
the SMPD1, NPC1 or NPC2 gene which leads to a shortage of enzymes and proteins
responsible for breaking down and moving lipids. This accumulation of lipids
leads to many symptoms including an enlarged spleen or liver, brain
degeneration, slurred speech, loss of muscle tone, clumsiness, seizers, and feeding
difficulties. However, symptoms vary in severity depending on the type; type A typically
being the most severe with nearly all patients dying in infancy. Niemann-Pick type
A and B is estimated to affect 1 in 250,000 people but type A is significantly
more prevalent in individuals from Ashkenazi Jewish decent, affecting roughly 1
in 40, 000 people (Genetics Home Reference). 
There is no cure for this disease. Individuals with type B and C typically
seek supportive treatment from physical therapists, cardiologists,
pulmonologists, and nutritionists to manage symptoms. Diagnosing individuals
with NP type C can be done through performing a filipin test which uses a florescent
polyene antibiotic with an affinity for binding to cholesterol. Type C is the
only type of NP that is characterized by a build up of cholesterol, so this
assay is not effective in diagnosing type A or B. The diagnosis of the disease is
determined from a test that shows an unusually high prevalence of cholesterol. This
test has many fallbacks such as the invasive nature of the test (requires a
skin biopsy), 5-7 week turnaround time, the high cost, and the limited amount
of testing centres with limited experienced staff. Another technique used to
identify this disease is genetic testing. There are 380 NPC1 and 22 NPC2 NP disease
causing mutations recorded in a database (Science Direct) and genetic testing
aims to identify the occurrence of any of these mutations in an individual’s
DNA. This is done by performing various molecular genetic techniques on a patient’s
blood or tissue sample. The diagnosis of Niemann-Pick disease is confirmed when
two alleles are found to carry a copy of a disease-causing mutation on NPC1 or
NPC2. One draw back to genetic testing is that some families host unique sequence
variants (mutations) which have never been recorded and would therefore not be
detected by genetic screening which only tests for known mutations. The test is
also relatively pricey and is therefore not accessible to some families who
might need it. Although genetic testing has its limitations, it is still beneficial
to families who have a history of Niemann Pick disease. Simple statistics show
that if two parents are heterozygous (carriers) for NP than there is a 25%
chance their child will have the disease and a 50% chance they are a carrier.
With genetic testing, individuals who want to start a family and have a known family
history of the NP disease can test to determine if they’re carriers because if only
one parent is a carrier than their child will not have the disease. This
information is useful for individuals wanting to start a family as there might
be hesitation around the idea of passing on this disease to their child,
especially because certain types are so severe and have a high mortality rate. With
genetic testing families can also decide to do prenatal testing which will
inform them of the disease status of their baby. Some individuals who have witnessed
other family members suffer from the disease may not want to pass on the
disease and may choose to have the pregnancy terminated if the test shows they
are homozygous for the allele. Genetic testing on individuals with no family
history of the disease is of much less importance as it is most likely that a
mutation would be hereditary rather than just appearing in an individual.
Genetic testing should be geared towards individuals with the intent of
starting a family but are aware that Niemann Disease runs in both individual’s
families as this will allow them to make an educated decision on pursuing a
child that may potentially carry this disease.