Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a genetic disorder that causes tumors to grow on nerves throughout the body. These tumors are usually noncancerous (benign). NF1 can affect the skin, bones, brain, and other body parts, leading to a range of symptoms that vary in severity among individuals.

What is Neurofibromatosis Type 1?

Neurofibromatosis type 1 (NF1) is a genetic condition that causes tumors to form on nerve tissue. These growths, called neurofibromas, are typically not cancerous but can appear anywhere in the body, including under the skin, along nerves, or in the brain. NF1 is a lifelong condition that affects about 1 in 3,000 to 4,000 people worldwide.

NF1 is one of several related disorders known as neurofibromatoses. It is the most common type. The condition is present from birth, though symptoms may develop and change over time, often becoming more noticeable during childhood or adolescence. While the tumors are usually benign, they can sometimes cause problems by pressing on nerves or other body parts. In rare cases, these tumors can become cancerous. NF1 can also lead to other health issues affecting the bones, eyes, and learning abilities. Managing NF1 involves regular monitoring and treatment of symptoms and complications as they arise. A team of specialists often works together to provide comprehensive care for individuals with NF1.

Symptoms

Symptoms of Neurofibromatosis type 1 (NF1) vary widely among individuals, even within the same family. Common signs include specific skin spots, freckling in unusual areas, and soft bumps on or under the skin. Many people with NF1 also experience learning difficulties or bone problems.

The most common symptoms of NF1 often appear on the skin. These include flat, light brown spots called café-au-lait spots, which are usually present from birth or develop in early childhood. A diagnosis of NF1 typically requires at least six café-au-lait spots, measuring at least 5 millimeters (mm) across before puberty or 15 mm after puberty. Another common skin symptom is freckling in unusual places, such as the armpits or groin. Small, soft bumps on or under the skin, called neurofibromas, are also characteristic. These usually appear during childhood or adolescence. People with NF1 often develop tiny, harmless bumps on the iris (the colored part of the eye) called Lisch nodules. Other symptoms can include tumors on the optic nerve (optic glioma), which can affect vision, and bone problems like scoliosis (a curve in the spine) or bowing of the legs. Some individuals may have a larger head size, shorter stature, or learning disabilities, including attention-deficit/hyperactivity disorder (ADHD). High blood pressure (hypertension) is also more common in people with NF1.

Causes & risk factors

Neurofibromatosis type 1 (NF1) is caused by a genetic mutation in the NF1 gene, located on chromosome 17. This gene is responsible for making a protein called neurofibromin, which helps control cell growth. When the gene mutates, neurofibromin doesn't work correctly, leading to uncontrolled cell growth and tumor formation.

The NF1 gene mutation can be inherited from a parent or can occur spontaneously. About half of all NF1 cases are inherited, meaning a child receives the mutated gene from one parent. NF1 is an autosomal dominant condition, which means only one copy of the mutated gene is needed for the condition to develop. If a parent has NF1, there is a 50% chance their child will also have it. In the other half of cases, the genetic mutation happens randomly at the time of conception, without either parent having the condition. This is known as a spontaneous mutation. In these instances, there is no family history of NF1. There are no known lifestyle or environmental risk factors for developing NF1. The only risk factor is having a parent with the condition or experiencing a spontaneous genetic mutation.

How it's diagnosed

Neurofibromatosis type 1 (NF1) is typically diagnosed based on a set of specific clinical criteria observed by a doctor. These criteria include characteristic skin findings, such as multiple café-au-lait spots and freckling, along with other physical signs. Genetic testing can confirm the diagnosis, especially in cases where the clinical signs are not fully clear.

A doctor will look for at least two of the following seven signs to diagnose NF1: * Six or more café-au-lait spots (flat, light brown skin patches) that are at least 5 mm across in children or 15 mm in adults. * Freckling in the armpit or groin area. * Two or more neurofibromas (soft bumps on or under the skin) or one plexiform neurofibroma (a larger tumor involving multiple nerves). * Two or more Lisch nodules (tiny, harmless bumps on the iris of the eye). * An optic glioma (a tumor on the nerve that connects the eye to the brain). * Specific bone lesions, such as sphenoid dysplasia (a bone defect in the skull) or thinning of the long bones. * A parent, sibling, or child who has been diagnosed with NF1. If a child has some but not all of these signs, a doctor may monitor them over time as symptoms can develop gradually. Genetic testing can be used to confirm the presence of a mutation in the NF1 gene, which can be helpful if the clinical diagnosis is uncertain or for family planning purposes.

Treatment options

There is no cure for Neurofibromatosis type 1 (NF1), so treatment focuses on managing symptoms and complications as they arise. This often involves regular monitoring by a team of specialists, surgical removal of problematic tumors, and medications to address specific issues like high blood pressure or certain types of neurofibromas.

Regular check-ups are crucial for people with NF1 to monitor for new symptoms or complications. These check-ups may involve physical exams, eye exams, and developmental assessments. A multidisciplinary team, including neurologists, dermatologists, ophthalmologists, orthopedists, and geneticists, often provides care. Surgery may be an option to remove neurofibromas that are painful, disfiguring, or pressing on nerves or organs. For certain inoperable plexiform neurofibromas (tumors that spread along nerves), especially in children, specific medications like selumetinib (Koselugo) may be prescribed to shrink the tumors. Other medications can help manage symptoms such as high blood pressure or attention-deficit/hyperactivity disorder (ADHD). Physical therapy can help address bone problems like scoliosis. Learning difficulties may be managed with special education support. While most tumors are benign, regular screening for any signs of malignant transformation is important, though rare.

Recovery & outlook

The outlook for individuals with Neurofibromatosis type 1 (NF1) varies greatly, as the severity of symptoms can range from mild to significant. Most people with NF1 live full and productive lives, though they may face ongoing medical challenges. Life expectancy is generally good, though it can be slightly reduced on average due to potential complications.

Many individuals with NF1 experience only mild to moderate symptoms that do not significantly impact their daily lives. They may have skin spots and a few neurofibromas but few other health issues. For others, NF1 can lead to more serious complications, such as vision problems, bone deformities, learning disabilities, or, rarely, cancerous tumors. Ongoing medical care and monitoring are important to manage symptoms and address any complications early. With appropriate management and support, many people with NF1 can achieve their educational and career goals. Support groups and resources can also help individuals and families cope with the challenges of NF1. While the risk of certain cancers is slightly higher in people with NF1, and life expectancy may be reduced by an average of 8 to 15 years compared to the general population, most individuals live well into adulthood. The specific outlook depends on the individual's unique set of symptoms and how well they are managed.

When to see a doctor

You should see a doctor if you notice any new or changing symptoms that concern you, especially if you or a family member has been diagnosed with Neurofibromatosis type 1 (NF1). Prompt medical attention is important for evaluating any potential complications or changes in your condition.

If you or your child has several café-au-lait spots, freckling in the armpits or groin, or soft bumps on the skin, it is important to consult a doctor for an evaluation. These could be early signs of NF1. For individuals already diagnosed with NF1, it is crucial to report any new symptoms or changes in existing ones to your healthcare provider. This includes changes in the size, shape, or pain level of neurofibromas, new vision problems, increasing pain, numbness or weakness, or any sudden changes in behavior or learning abilities. Regular follow-up appointments with your NF1 care team are essential for ongoing monitoring and management. Do not hesitate to seek medical advice if you have any concerns about your health or the health of a loved one with NF1.

Frequently asked questions

Is Neurofibromatosis Type 1 (NF1) always severe?

No, the severity of Neurofibromatosis type 1 (NF1) varies greatly among individuals. Some people experience only mild symptoms, such as skin spots and a few noncancerous tumors, while others may face more significant challenges like bone problems, learning difficulties, or vision issues. The condition's impact can differ even within the same family.

Can Neurofibromatosis Type 1 (NF1) be prevented?

Neurofibromatosis type 1 (NF1) cannot be prevented because it is a genetic condition caused by a mutation in the NF1 gene. This mutation can be inherited from a parent or occur spontaneously at conception. There are no known lifestyle or environmental factors that can prevent the development of NF1.

Is Neurofibromatosis Type 1 (NF1) a type of cancer?

Neurofibromatosis type 1 (NF1) is not a type of cancer itself, but it increases the risk of developing certain cancers. The tumors (neurofibromas) associated with NF1 are usually noncancerous (benign). However, in rare cases, these benign tumors can transform into malignant (cancerous) tumors, or other types of cancer may develop.

How is Neurofibromatosis Type 1 (NF1) inherited?

Neurofibromatosis type 1 (NF1) is inherited in an autosomal dominant pattern. This means that a child only needs to inherit one copy of the mutated NF1 gene from either parent to develop the condition. If a parent has NF1, there is a 50% chance their child will inherit the condition. About half of all NF1 cases are inherited, while the other half result from new, spontaneous gene mutations.

What kind of doctors treat Neurofibromatosis Type 1 (NF1)?

Neurofibromatosis type 1 (NF1) is often managed by a multidisciplinary team of specialists. This team may include neurologists, dermatologists, ophthalmologists, orthopedists, geneticists, and developmental pediatricians. Regular check-ups with these specialists help monitor symptoms and address any complications that may arise.

Are there new treatments for Neurofibromatosis Type 1 (NF1)?

While there is no cure for Neurofibromatosis type 1 (NF1), new treatments are emerging for specific complications. For example, the medication selumetinib (Koselugo) has been approved to treat inoperable plexiform neurofibromas in children, which are tumors that can cause significant problems. Research continues to explore other potential therapies for NF1-related issues.

Sources

• MedlinePlus — Neurofibromatosis Type 1
• Mayo Clinic — Neurofibromatosis Type 1
• Cochrane Library — Neurofibromatosis Type 1