Although most cases of NF1 are mild to moderate, NF1 can lead to disfigurement; blindness; skeletal abnormalities; dermal, brain, and spinal tumors; loss of limbs; malignancies; and learning disabilities. NF1 also has a connection to developmental problems, especially learning disabilities, which are five times more common in the NF1 population than in the general population. The distinguishing feature of NF2 is tumors that grow on the eighth cranial nerve in both ears, commonly causing deafness and severe balance problems.
NF2 brings on increased risk of other types of nervous system tumors as well. In some cases, optic gliomas have no effect on vision. Additional signs and symptoms of neurofibromatosis type 1 vary, but they can include high blood pressure hypertension , short stature, an unusually large head macrocephaly , and skeletal abnormalities such as an abnormal curvature of the spine scoliosis. Mutations in the NF1 gene cause neurofibromatosis type 1.
The NF1 gene provides instructions for making a protein called neurofibromin. This protein is produced in many cells, including nerve cells and specialized cells surrounding nerves oligodendrocytes and Schwann cells. Neurofibromin acts as a tumor suppressor, which means that it keeps cells from growing and dividing too rapidly or in an uncontrolled way.
Mutations in the NF1 gene lead to the production of a nonfunctional version of neurofibromin that cannot regulate cell growth and division. As a result, tumors such as neurofibromas can form along nerves throughout the body. Neurofibromatosis type 1 is considered to have an autosomal dominant pattern of inheritance.
People with this condition are born with one mutated copy of the NF1 gene in each cell. In about half of cases, the altered gene is inherited from an affected parent.
The remaining cases result from new mutations in the NF1 gene and occur in people with no history of the disorder in their family. Unlike most other autosomal dominant conditions, in which one altered copy of a gene in each cell is sufficient to cause the disorder, two copies of the NF1 gene must be altered to trigger tumor formation in neurofibromatosis type 1.
A mutation in the second copy of the NF1 gene occurs during a person's lifetime in specialized cells surrounding nerves. Almost everyone who is born with one NF1 mutation acquires a second mutation in many cells and develops the tumors characteristic of neurofibromatosis type 1. Genetics Home Reference has merged with MedlinePlus.
Learn more. The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health. Neurofibromatosis type 1. From Genetics Home Reference. Although some cutaneous neurofibromas arise in childhood, most start appearing during or after the teenage years.
Freckling in the armpits or the groin Freckling usually appears by 3 to 5 years of age. Freckling can occur in other conditions, but not with the other symptoms and concerns of NF1. A tumor of the optic pathway called an optic pathway glioma.
These tumors typically first appear by age 6, rarely in late childhood and adolescence, and almost never in adults. Although they can affect vision, most do not become symptomatic. Bone deformities Abnormal development of the eye socket sphenoid or the tibia one of the long bones of the shin. Short stature and larger than normal head circumference Children with NF1 are usually shorter than average and have larger heads. Cardiovascular complications , such as congenital heart defects, high blood pressure hypertension , and constricted, blocked, or damaged blood vessels.
NF1 should be evaluated periodically by an NF1 specialist, even if they are not experiencing symptoms, to evaluate for signs or symptoms that may indicate a need for treatment and to provide reassurance that treatment is not needed when appropriate. In April the U. Food and Drug Administration approved selumetinib Koselugo as a treament for children ages 2 years and older wth neurofibromatosis type 1.
The drug helps to stop tumor cells from growing. Neurofibromatosis 2 NF2 is less common than NF1. Approximately 50 percent of affected people inherit the abnormal gene familial ; in others the condition is caused by a spontaneous genetic mutation in the NF2 gene. Each child of an affected parent has a 50 percent chance inheriting the abnormal NF2 gene. Benign, slow-growing tumors affecting the cranial, spinal, and peripheral nerves, as well as the covering of the brain and spinal cord called the meninges.
Visual problems. People with NF2 may develop cataracts at an earlier age or changes in the retina that can affect vision. Peripheral neuropathy. Individuals with NF2 may develop problems with nerve function , usually numbness and weakness on both sides of the body with or without muscle loss in the arms and legs.
While teenagers and adults often are first seen for hearing and balance problems, young children with NF2 more commonly seek initial medical attention due to vision problems and meningiomas. Signs of NF2 may be present in childhood but can be overlooked, especially in children who do not have a family history of NF2.
Children are often first seen by a doctor because of schwannomas in the skin, vision loss from retinal abnormalities or tumors, seizures, or weakness related to spinal cord compression.
More commonly, symptoms of NF2 are first noticed in the second decade of life. The most common first symptom is hearing loss or ringing in the ears tinnitus related to vestibular schwannomas. Less often, the first visit to a doctor will be because of disturbances in balance, visual impairment, focal weakness in an arm or leg, seizures, or skin tumors. NF2 is best managed at a specialty clinic with an initial screening and annual follow-up evaluations more frequent if the disease is severe.
Improved diagnostic technologies, such as magnetic resonance imaging MRI , can reveal tumors of the vestibular nerve as small as a few millimeters in diameter.
Vestibular schwannomas grow slowly, but they can grow large enough to engulf one of the eighth cranial nerves and cause brain stem compression and damage to surrounding cranial nerves. Surgical options depend on tumor size and the extent of hearing loss. There is no general agreement among doctors about when surgery should be performed or which surgical option is best.
Individuals considering surgery should carefully weigh the risks and benefits of all options to determine which treatment is right for them. If hearing is lost during this surgery, but the auditory nerve is maintained, the surgical placement of a cochlear implant a device placed in the inner ear, or cochlea, that processes electronic signals from sound waves to the auditory nerve may be an option to improve hearing.
As tumors grow larger, it becomes harder to surgically preserve hearing and the auditory nerve.
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