Neurofibromatosis (commonly abbreviated NF) is
a genetically-inherited disorder in which the
nerve tissue grows tumors (neurofibromas) that may be benign or may cause
serious damage by compressing nerves and other tissues. This disease affects male and
female equally. This kind of disorder is resulted by gene mutation and affects
all neural crest cells in our body such as Schwann cells, melanocytes and
endoneurial fibroblasts. Cellular elements from these cell types proliferate
excessively throughout the body, forming tumors; melanocytes also function
abnormally in this disease, resulting in disordered skin pigmentation. The
tumors may cause bumps under the skin, colored spots, skeletal problems,
pressure on spinal nerve roots, and other neurological problems.
Neurofibromatosis is an autosomal dominant disorder, which means
this kind of disease can develop starting with only one copy of the affected
gene. If both parents has this disease the children will have this disease for
sure and when only one parent has it, the child will have a 50% of chance in
getting this disease.
Classifications
This
disorder is divided into three categories, NF 1, NF 2, Schwanommatosis; based on the different types of gene mutation, and the type of
protein that is missing. NF 1 is caused by gene
mutation on chromosome 17. It causes the lack of the Neurofibromin protein. NF2
is caused by gene mutation on chromosome 22. It causes the lack of
the Merlin protein. Schwanommatosis is caused by gene mutation on
chromosome 22 as well, but the missing protein is different from NF2. The
missing protein is called SMARCB1.
Types of Disease
|
Protein missing
|
NF1
|
Neurofibromin (a regulator of the GTPase activating enzyme
(GAP))
|
NF2
|
Merlin (cytoskeletal protein)
|
Schwanommatosis
|
SMARCB1
|
All three types of NF can cause several types
of tumors to grow.
Including:
Gliomas - Tumors made of glial
cells.
Meningiomas - Tumors arising from cells of the
meninges (the protective layer surrounding the brain and spinal cord)
Schwannomas - tumors made of schwann cells,
arising from the myelin sheath that protects our nerves.
Each type of tumors have different
characteristics, growth rate and reaction to every treatment methods.
That's why it is VERY important to study and
understand the natural history of Neurofibromatosis when treating a
patient with this genetic disorder, because using the wrong type of surgical
approach for the wrong type of tumor can cause detrimental and irreversible
effects on the patient.
I would emphasize this: NF patients who are
treated by doctors familiar with this conditon, whose condition is carefully
monitored and planned in the long-term, can live full and active lives. In more
developed countries like the U.S. patients can live active and high achieving
lives despite battling Neurofibromatosis. Some NF patients in the U.S. even run
marathons and climb Mount Kilimanjaro to raise awareness for this genetic disorder.
On the other hand, other patients who were treated by doctors that lack
the experience or knowledge in the treatment of NF can become paralyzed and
even lose their life after one or two surgeries.
Many would emphasize on how tragic and
devastating this condition is, to get a reaction from their readers or
listeners. But I personally prefer to emphasize that what we really need is for
doctors to treat us carefully. Plan our treatments carefully and not remove our
tumors forcibly just because the tumors exist. Not every tumor that exist has
to be removed. If the risk of removing a tumor far outweighs the benefit
of removing it, the doctor should consider alternative treatment
methods.
More often than not, patients fail to do
their own research and understand about a particular tumor or
their options, and blindly agree to their doctor's decision to
operate on a tumor. This is very common in less developed countries, even in
Malaysia. So my other emphasis would be to encourage the public to
understand their health and condition, and not to simply rely on their doctors.
Signs and symptoms:
Patients
with neurofibromatosis can be affected in many different ways. Morbidity is
often a result of plexiform neuromas, optic gliomas, or acoustic neuromas, but
mortality can also be associated with malignant transformation of the neuromas,
such as neurofibrosarcomas (often there is a malignant transformation in less
than 3% of the cases of NF1). Neurofibromatosis also increases the risk of leukemia
particularly in children; Children with NF-1 have 200 to 500 times the normal
risk of developing leukemia compared to the general population. Since the tumors grow where there are nerves, they can also
grow in areas that are visible, causing considerable social suffering for those
affected. The tumors can also grow in places that can cause other medical
issues that may require them to be removed for the patient's safety. Affected
individuals may need multiple surgeries (such as reduction surgery, or Gamma
knife surgery), depending on where the tumors are located. For instance, those
affected with NF 2 might benefit from a surgical decompression of the
vestibular tumors to prevent deafness.
Diagnostic Features of
Neurofibromatosis
There is no medical
test available to definitively diagnose neurofibromatosis. The only way to tell
that a person is affected is to examine him or her to see if there are signs of
the disorder. There are several features that your doctor will look for, and it
is generally agreed that anyone having at least two of the features on this
list has NF1.
• 6 or more
cafe-au-lait spots ( Brown patches)
• freckling under the arms or in the
groin
• 2 or more neurofibromas
• Lisch nodules (tiny, tan bumps) on the iris
of the eye • optic nerve tumor (optic glioma)
• characteristic bone
abnormality
• family history of NF1
Diagnosis:
Prenatal testing:
Embryo: For embryos produced by
in vitro fertilization it
is possible via pre-implantation
genetic diagnosis (PGD) to screen for NF-1.
PGD has about 95-98% accuracy but requires that the partner with NF2 have a recognizable genetic
mutation, which is only the case for about 60% of people with a clinical
diagnosis of NF2. PGD cannot be used to detect Schwannomatosis, because the gene for
it has not yet been identified.
Treatment:
There is no cure for the condition itself, the only
therapy for patients with neurofibromatosis is a program of treatment by a team
of specialists to manage symptoms or complications. Surgery may be needed when
the tumors compress organs or other structures. Less than 10% of people with
neurofibromatosis develop cancerous growths; in these cases, chemotherapy may
be successful. Genetic screening and counseling is available for family with NF.