Neurofibromatosis, also known as NF,
is a genetically inherited disorder of the nervous system (brain and spinal
cord) which mainly affects the development of nerve (neural) cell tissues,
causing tumors (neurofibromas) to develop on nerves, and may cause other
abnormalities. The tumors may be harmless, or may compress nerves and other
tissues and cause serious damage. In some rarer cases the tumors may become
cancerous.
Neurofibromatosis affects all neural crest cells (Schwann cells, melanocytes, endoneurial fibroblasts). Elements from these cells proliferate in excess throughout the whole body, resulting in the formation of tumors, and abnormal function of melanocytes, causing disordered skin pigmentation. Melanocytes are pigment-producing cells in the skin, hair and eye that determine their color. The tumors may also cause bumps under the skin, colored spots, bone problems, pressure on spinal nerve roots, as well as other neurological problems.
Neurofibromatosis may affect the bones, causing severe pain. Some patients experience learning disabilities, behavioral problems, and vision and/or hearing loss. There is no cure for the disease.
Neurofibromatosis describes two entirely different diseases, as well as a much rarer form, with different causes that have similar features:
Neurofibromatosis affects all neural crest cells (Schwann cells, melanocytes, endoneurial fibroblasts). Elements from these cells proliferate in excess throughout the whole body, resulting in the formation of tumors, and abnormal function of melanocytes, causing disordered skin pigmentation. Melanocytes are pigment-producing cells in the skin, hair and eye that determine their color. The tumors may also cause bumps under the skin, colored spots, bone problems, pressure on spinal nerve roots, as well as other neurological problems.
Neurofibromatosis may affect the bones, causing severe pain. Some patients experience learning disabilities, behavioral problems, and vision and/or hearing loss. There is no cure for the disease.
Neurofibromatosis describes two entirely different diseases, as well as a much rarer form, with different causes that have similar features:
§ Type 1 neurofibromatosis (Nf1) - or von Recklinghausen's disease, von
Recklinghausen NF, or peripheral neurofibromatosis. It is transmitted on
chromosome 17 and is mostly caused by mutation (rather than deletion) of the
Nf1 gene.
Shortly after birth several birthmarks (hyperpigmentation) may appear in different parts of the body. During late childhood cutaneous lesions (tumors on the skin) and subcutaneous lesions (tumors under the skin) may appear, from a few to thousands. There is a slight risk that the tumors become cancerous.
For some patients this is presents no serious medical problems apart from a skin condition. However, complications are possible, and sometimes serious.
Shortly after birth several birthmarks (hyperpigmentation) may appear in different parts of the body. During late childhood cutaneous lesions (tumors on the skin) and subcutaneous lesions (tumors under the skin) may appear, from a few to thousands. There is a slight risk that the tumors become cancerous.
For some patients this is presents no serious medical problems apart from a skin condition. However, complications are possible, and sometimes serious.
§ Type 2 neurofibromatosis (Nf2) - or bilateral neurofibromatosis. It results mainly
from a mutation (rather than a deletion) of the Nf2 gene and is transmitted on
chromosome 33.
Tumors form in the nervous system, generally within the skull, known as intracranial tumors. Tumors also develop in the spinal canal, known as intraspinal tumors. Acoustic neuromas are common - these develop on the vestibulocochlear nerve (the eighth cranial nerve). The vestibulocochlear nerve is responsible for our sense of hearing; it is also important for our sense of balance and body position. Patients may experience hearing loss, as well as losing their sense of balance. Symptoms tend to occur during late teens and early 20s. Tumors may also become cancerous.
Tumors form in the nervous system, generally within the skull, known as intracranial tumors. Tumors also develop in the spinal canal, known as intraspinal tumors. Acoustic neuromas are common - these develop on the vestibulocochlear nerve (the eighth cranial nerve). The vestibulocochlear nerve is responsible for our sense of hearing; it is also important for our sense of balance and body position. Patients may experience hearing loss, as well as losing their sense of balance. Symptoms tend to occur during late teens and early 20s. Tumors may also become cancerous.
§ Schwannomatosis - this is a much rarer form of
neurofibromatosis that has only recently been recognized. It is genetically
distinct from Nf1 and Nf2. According to the National Institute of Neurological
Disorders and Stroke, USA, schwannomatosis accounts for about 15% of the
inherited forms of neurofibromatosis. Patients develop schwannomas (tumors in
the tissue around a nerve) anywhere in the body, except for the
vestibulocochlear nerve (the nerve that goes to the ear). The tumors can cause
severe pain, numbness, tingling, and/or weakness in the toes and fingers.
Patients do not develop the neurofibromas seen in Nf1 and Nf2.
Researchers have identified a mutation of the SMARCB1/INI1 gene that is linked to the familial form of the disease. However, nobody yet knows what causes the severe pain which is typical in this disorder.
Researchers have identified a mutation of the SMARCB1/INI1 gene that is linked to the familial form of the disease. However, nobody yet knows what causes the severe pain which is typical in this disorder.
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