Peripheral type neurofibromatosis

Peripheral type neurofibromatosis (PNF), also known as Neurofibromatosis type 1 (NF1) or von Recklinghausen's disease, is a genetic disorder characterized by the development of multiple noncancerous (benign) tumors of nerves and skin (neurofibromas) and areas of abnormal skin color (pigmentation). The condition is caused by mutations in the NF1 gene, which is responsible for the production of a protein called neurofibromin that helps regulate cell growth. The disorder affects 1 in 3,000 people worldwide and has a variable presentation, even among members of the same family.

Symptoms and Signs

The symptoms of PNF can vary widely among affected individuals. Common signs include:

• Café-au-lait spots: Light brown skin patches, which may be present at birth or appear in the first years of life.
• Neurofibromas: These benign tumors can develop on or under the skin, or along the nerves throughout the body, including the brain and spinal cord.
• Lisch nodules: Harmless tiny bumps on the iris of the eye.
• Bone deformities: Such as scoliosis (curvature of the spine) or tibial dysplasia (bowing of the lower legs).
• Learning disabilities: Although intelligence is usually normal, children with NF1 may have learning disabilities.

Diagnosis

Diagnosis of PNF is primarily based on clinical criteria. A person is diagnosed with NF1 if they have two or more of the following features:

• Six or more café-au-lait spots over 5 mm in diameter in prepubertal individuals and over 15 mm in postpubertal individuals.
• Two or more neurofibromas of any type or one plexiform neurofibroma.
• Freckling in the armpit or groin area.
• Optic glioma (a type of brain tumor).
• Two or more Lisch nodules.
• A distinctive bone lesion such as sphenoid dysplasia or thinning of the cortex of the long bones.
• A first-degree relative (parent, sibling, or child) with NF1 according to the above criteria.

Genetics

PNF is an autosomal dominant disorder, meaning that only one copy of the altered gene is sufficient to cause the disorder. About half of the cases result from new mutations in the gene and occur in people with no history of the condition in their family. The NF1 gene is located on chromosome 17 and encodes the neurofibromin protein, which negatively regulates the RAS/MAPK pathway, a key pathway in cell growth and differentiation.

Treatment

There is no cure for PNF, but treatments are available to manage symptoms and complications. Management may include:

• Regular monitoring for the development of complications, such as malignant peripheral nerve sheath tumors.
• Surgical removal of painful or disfiguring neurofibromas.
• Treatment of learning disabilities with educational support.
• Management of bone deformities and other orthopedic issues.
• Pain management.

Prognosis

The prognosis for individuals with PNF varies. While many people live normal and productive lives, individuals with NF1 may have a slightly reduced life expectancy due to complications such as malignant peripheral nerve sheath tumors and cardiovascular issues. Early diagnosis and management of complications can improve quality of life and outcomes.

Peripheral type neurofibromatosis Resources
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