Neurofibromatosis

Updated July 1, 2019

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When a loved one is facing a serious diagnosis like that of neurofibromatosis, you need answers to your questions you can rely on. Here at YourDNA.com, we've done the research and compiled this guide to give you the answers you need in language you can understand. We realize knowledge is power, that's why we're here.

What's in this Guide?

Disclaimer: Before You Read

It is important to know that your genes are not your destiny. There are various environmental and genetic factors working together to shape you. No matter your genetic makeup, maintain ideal blood pressure and glucose levels, avoid harmful alcohol intake, exercise regularly, get regular sleep. And for goodness sake, don't smoke.

Genetics is a quickly changing topic. Read More...

What Is Neurofibromatosis?

Neurofibromatosis is a genetic disorder that affects the nervous system 1. The primary concern with this disorder is that it causes issues with how nerve cells form and grow.

Neurofibromatosis (NF) makes tumors grow on nerves in the body. These tumors are normally benign, however, it is possible for these tumors to be cancerous. This disorder can lead to many deformities which can affect a patients on a day to day basis.

Neurofibromatosis can be inherited from one's parents or it can happen due to a mutation in one's genes. Once a person has this disorder, it is possible to pass it to their children. Neurofibromatosis is a lifelong disorder which affects people of all different ethnicities and genders, equally.

There are three different types of neurofibromatosis:

  • Neurofibromatosis Type 1 (NF1): This is the most common type of NF. It affects approximately 1 in 3,000 people throughout the world. This type can cause changes in the skin and bone deformities. It usually starts in childhood. These symptoms are sometimes present at birth.
  • Neurofibromatosis Type 2 (NF2): This is a less common type of NF. It affects approximately 1 in every 25,000 people in the world. This type can cause hearing loss, ringing in the ears, and poor balance. These symptoms generally start in the teenage years.
  • Schwannomatosis: This type is the rarest type of neurofibromatosis, affecting 1 out of every 40,000 people in the world. It causes intense pain due to tumor growth on the spine and peripheral nerves.

Symptoms of Neurofibromatosis

The symptoms of neurofibromatosis differ from person to person and from type to type. It is important to note that all patients experience neurofibromatosis differently and the severity will differ between patients.

Many patients are mildly affected by this diagnosis while others have severe symptoms. Due to the differences between the various types of NF, we will discuss the symptoms based on each type.

NF1 Symptoms 2

Café Au Lait spots: These are light brown spots that are flat on the skin. These spots are not harmful to the individual who has them. They can, however, cause the patient with the spots to have body image impairment when in visible places such as the face.

Neurofibromas: These are the typical NF1 lumps. These bumps appear under and on the skin. These bumps are generally not medical issues, however, they can cause pain and itching along with body image impairment to those who have them. Some individuals only present with a few of these bumps in number where others can have hundreds on their body.

Plexiform neurofibromas: These are a much less common type of neurofibroma and occur in approximately 25% of people with NF1. These neurofibromas can grow very large and cause complications such as putting pressure on nerves and organs. In about 10% of this type of neurofibroma, it becomes malignant.

Cognitive challenges: Intelligence levels with those with NF1 are typically within the normal range, however, children with NF1 may need more help in school. In approximately 50% of all NF1 cases, learning difficulties occur in children.

Optic pathway tumors: The nerve behind the eye is called the optic nerve. In NF1, tumors called optic glioma may occur and develop in the cells that surround the optic nerve. Approximately 15% of those with NF1 will develop this type of tumor. Children under the age of six years are at the highest risk for developing this an optic glioma. Many times, optic gliomas do not cause symptoms. However, they can occasionally affect vision and require chemotherapy to treat.

Delayed or early puberty: Although most individuals with NF1 will begin puberty at a normal age, some may experience precocious (early) or delayed puberty.

Small stature: This is another symptom of NF1. Approximately 30% of those with NF1 will have a small stature and need to be treated with growth hormone.

High blood pressure: This is a very serious complication for a small fraction of individuals with NF1. Those with NF1 should get their blood pressure assessed annually.

Bone issues: A curvature of the lower leg bone or tibia is seen in approximately 5% of patients. A curvature in the spine or scoliosis is also seen in approximately 12-20% of the patients with NF1.

NF2 Symptoms 3

Hearing and balance issues: NF2 is usually characterized by hearing and balance difficulties. This is due to tumor growth on the eighth cranial nerves (or the nerves leading to the ears).

Vestibular schwannomas: These are the hallmark tumors in patients with NF2. These are benign tumors which can cause hearing loss in one or both of the ears. Vestibular schwannomas are abnormal Schwann cells. These cells give lining and insulation to the nerves that they need in order to conduct information.

Meningiomas: These are benign, contained tumors on the lining of the brain and spinal cord. Approximately 80% of people with NF2 will develop meningiomas in their lifetime. These can cause severe symptoms such as headaches, seizures and numbness. However, most do not cause symptoms until they are noticeable in size.

Ependymomas: These tumors develop in about 20% of people with NF2. They are located on the cells lining the ventricles of the brain and the center of the spinal cord.

Nerve damage: Since all of the nerves in the body are associated with different functions, damage can happen to the senses, muscles, and organs. Nerve damage may happen in individuals with NF2 and may include some of the following symptoms:

  • Ringing in the ears (tinnitus)
  • Problems with balance
  • Facial weakness
  • Vision loss
  • Brain and cranial nerve damage
  • Hearing loss
  • Swallowing difficulties
  • Seizures
  • Loss of balance and mobility due to spinal tumors
  • Peripheral neuropathy
  • Pain
  • Muscle wasting
  • Drop foot/foot drop

Schwannomatosis Symptoms 4

This is a painful type of NF. Tumors grow on peripheral nerves causing pain that is sometimes greater than the size of the tumor. Pain can range anywhere from mild to severe.

Unlike Neurofibromas in NF1, these tumors grow deep within the patient's body resulting in pain when the tumor presses a nerve against a bony structure. Other symptoms related to schwannomatosis include but are not limited to:

  • Numbness or tingling
  • Vision changes
  • Weakness, including facial weakness
  • Headaches
  • Bowel dysfunction or difficulty urinating

Neurofibromatosis and Genetics

People are diagnosed with neurofibromatosis either because they inherited it from their parents or because of a gene mutation in the sperm or egg cells. NF1 and NF2 are caused by two different abnormal genes that can be inherited from their parents 5.

NF is an autosomal dominant disorder. The abnormal gene for NF1 is located on chromosome 17 and the abnormal gene for NF2 is located on chromosome 22.

Since this gene is autosomal dominant, any individual with NF that wishes to be a parent (regardless of the type), has a 50% chance of passing this gene down to their children.

This means that each child they have has a 50/50 chance of developing this disorder if one parent has NF. Since the gene mutation is located on different chromosomes for the different types of NF, the type of NF the child inherits will be the same as their parent.

This means that if a parent has NF1, their child has a 50% chance of inheriting NF1.

Diagnosis of Neurofibromatosis

The diagnosis criteria are different for the different types of NF. Genetic testing is available in most cases through a simple blood test. However, it is not typically done to diagnose NF.

A diagnosis based on the information below can be made with a family history and physical examination of the patient as soon as they begin to have symptoms.

Diagnosis in NF1 is primarily based off of a medical examination. In order for a patient to be diagnosed with NF1 they must meet TWO of the following criteria:

  • Six or more café au lait spots that are 5 mm or greater in pre-pubertal children or 15 mm or greater in post-pubertal adolescents or adults
  • Two or more neurofibromas of any kind, or one or more plexiform neurofibromas
  • Freckling on the underarm
  • Optic glioma
  • Two or more Lisch nodules, which are benign colored spots in the eye
  • A bony lesion that is distinctive: dysplasia or abnormal growth of the sphenoid bone behind the eye, or dysplasia of long bones, many times in the lower leg
  • Have a close relative (parent, sibling, or child) with NF1

The diagnosis of NF2 is made when one of the following collections of signs and symptoms occur.

  • Bilateral vestibular schwannomas (on both ears)
  • A first degree relative with NF2, PLUS: Unilateral (on one ear) vestibular schwannoma

OR Any two of the following:

  • Meningioma
  • Juvenile cataracts
  • Glioma
  • Schwannoma
  • Neurofibroma (OR unilateral vestibular schwannoma)
  • Multiple meningiomas (two or more) PLUS Unilateral vestibular schwannoma

A diagnosis of schwannomatosis is made when a patient meets one of the following criteria:

  • Two or more non-intradermal schwannomas, one with the confirmation of pathology, including no bilateral vestibular schwannoma by high-quality MRI.
  • Confirmation of one pathological schwannoma or intracranial meningioma, AND a first-degree relative like a parent or a sibling that has been affected by NF.
  • OR - in the case that two or more non-intradermal tumors occur but none has been pathologically proven to be a schwannoma it will be considered a possible diagnosis; with this possible diagnosis, the occurrence of chronic pain with the development of tumors increases the likelihood of schwannomatosis.

Is Prenatal Diagnosis for Neurofibromatosis Available?

Genetic testing in the form of amniocentesis or chorionic villus sampling can be done during pregnancy to detect whether or not a fetus has the presence of a mutation in the NF1 gene or not. Prenatal genetic testing for NF2 may be available, however, only 65% of those tested get an accurate diagnosis from that genetic test. There is currently no prenatal genetic test for schwannomatosis 6.

Who Should Be Screened for Neurofibromatosis?

Those who have first degree relatives with neurofibromatosis should be tested throughout adolescence into adulthood to make sure they do not show any of the signs or symptoms of of the disease. Any individual that has pain, abnormal lesions or tumors on the skin, hearing loss, balance complications and/or cognitive delays should consult a physician for a formal screening.

Neurofibromatosis Treatment Options

Although gene therapy is something in research currently, it is not a current treatment option for individuals with NF. Since there is no cure for NF, treatment focuses on treating the symptoms caused by the tumors.

Health care professionals that may be involved in the care of a patient with NF1 include but are not limited to ophthalmology, neurology, dermatology, orthopedics, oncology, pediatrics, genetic counseling, psychology, and cardiology.

The management for NF2 is very similar to NF1. Many of the same providers will be on the team of health care professionals to care for this disorder. However, one physician to add would be an otolaryngologist (ear, nose, and throat), physician. This health care professional will know how to check for hearing loss and bilateral vestibular schwannomas.

Currently, there is no cure and no effective medication treatment for schwannomatosis. Management for this type of Neurofibromatosis is controlling specific symptoms that a person may develop. Surgical interventions to remove the schwannomas (tumors) are available for severe cases.

Prognosis of Neurofibromatosis

Although NF1 is a progressive disease and their symptoms will worsen over time. Individuals with NF1 have a normal life expectancy. Since NF2 and schwannomatosis are rare, few studies have been done to determine whether or not Neurofibromatosis will shorten their life expectancy.

We do know that symptoms in both NF2 and Schwannomatosis can decrease the quality of life if the patient's symptoms are severe. Neurofibromatosis, regardless of the type, cannot be cured.

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Referenced Sources

  1. Neurofibromatosis.
    U.S. National Library of Medicine. 2019.
  2. Newly diagnosed with NF1 : A guide to the basics.
    Children's tumor foundation. Retrieved online June 2019.
  3. Newly diagnosed with NF2 : A guide to the basics.
    Childrens tumor foundation. Retrieved 2019.
  4. Schwannomatosis.
    Children's Tumor Foundation. Retrieved 2019.
  5. About neurofibromatosis.
    National Human Genome Research Institute. Retrieved 2019.
  6. Neurofibromatosis fact sheet.
    National Institute of Neurological Disorders and Stroke. Retrieved 2019.