Neurofibromatosis-1

Definition

Neurofibromatosis-1 is an inherited disorder characterized by formation of neurofibromas (tumors involving nerve tissue) in the skin, subcutaneous tissue, cranial nerves, and spinal root nerves.

Causes, incidence, and risk factors

NF1 is an autosomal dominant trait, meaning that if either parent has NF1, their children have a 50% chance of inheriting the disease. NF1 also appears in families with no previous history of the condition, as a result of a new genetic mutation in the particular sperm or egg that created the child. NF1 is caused by abnormalities in one of the genes encoding a protein called neurofibromin.

Neurofibromatosis causes unchecked growth of neurofibromatous tissue in nerves, which can put pressure on affected nerves and cause pain and severe nerve damage. This leads to loss of function in the area served by the nerve. Problems with sensation or movement can occur as a result, depending on the particular nerves affected.

Symptoms

Symptoms can be extremely varied, depending on the age of the patient and severity of the disease.

Symptoms may include:

• Mild impairment of intellectual function, attention deficit disorder
• Fracture of the long bones of the leg in early childhood
• "Coffee with milk" (cafe-au-lait) spots on the skin
• Freckles in the underarm or groin
• Convulsions
• Pain (associated with affected peripheral nerves)
• Blindness
• Rubbery tumors of the skin called nodular neurofibromas
• Soft tumors called plexiform neurofibromas which may have a darker color

Signs and tests

The diagnosis of neurofibromatosis is generally made based on physical findings. The cafe-au-lait spot (meaning literally the color of coffee with cream) is the hallmark of neurofibromatosis. Although many healthy people have 1 or 2 small cafe-au-lait spots, adults with 6 or more spots greater than 1.5 cm in diameter are likely to have neurofibromatosis.

Other signs include:

• Freckling in the armpits, groin, or underneath the breast in women
• Multiple soft tumors apparent on the skin or deeper in the body viewed by radiologic testing (scans)
• Soft nodules under the skin
• Large infiltrating tumors under the skin (plexiform neurofibromas) which can cause disfigurement
• Pigmented, raised spots on the colored part (iris) of the eye (Lisch nodules)

• Examination by a doctor familiar with NF1, such as a neurologist, geneticist, or dermatologist
• Eye exam by an ophthalmologist familiar with NF1
• MRI of the affected site
• Removal of skin lesions
• Other specific tests associated with complications
• Genetic testing that demonstrates a mutation in the neurofibromin gene

Treatment

There is no specific treatment for neurofibromatosis. Tumors that cause pain or loss of function are removed on an individual basis. Tumors that have grown rapidly should be removed promptly as they may become malignant. Experimental treatments for severe tumors are under investigation.

Special schooling for those with learning disorders and/or attention-deficit disorder may be required in some cases. Annual eye exams are strongly recommended.

Support Groups

For more information and resources, contact the National Neurofibromatosis Foundation.

Expectations (prognosis)

The life expectancy of people with neurofibromatosis is almost normal, barring complications. Although mental impairment is generally mild, NF1 is a known cause of attention deficit hyperactivity disorder in a minority of patients.

With appropriate education and job expectations, people with neurofibromatosis can live a normal life. Some individuals manifest hundreds of tumors on their skin and are subject to stigmatization by society because of the way they look.

Patients with neurofibromatosis have an increased chance of developing severe tumors which, rarely, can shorten life span.

Complications

• Blindness caused by a tumor in an optic nerve (optic glioma)
• Malignant transformation of tumors (in approximately 5-10% of affected individuals)
• Chance of pheochromocytoma, which causes very high blood pressure
• Loss of nerve function in nerves where a neurofibroma's growth has caused prolonged pressure on the nerve
• Attention deficit hyperactivity disorder (ADHD)
• Cosmetically significant tumors of the face, skin, and other exposed areas
• Bowing or breakage of the leg bones with poor healing
• Scoliosis or curvature of the spine

Calling your health care provider

Call your health care provider if you notice coffee-with-cream colored spots on your child's skin or any of the signs listed here. Also call if you have a family history of neurofibromatosis and are planning to have children or would like to have your child examined.

Prevention

Genetic counseling is recommended for anyone with a family history of neurofibromatosis.

Illustrations

Neurofibroma

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NF1; Von Recklinghausen neurofibromatosis ; nf1; neurofibromas nf1