Types of neurofibromatosis


Neurofibromatosis is the general name for a group of complex genetic disorders that can lead to various medical conditions and cause tumors to develop and grow anywhere in the nervous system. Tumors, usually benign (non-cancerous), can grow in the brain, along the spinal cord and on or near nerves anywhere in the body, including the skin surface. The condition is divided into three main types, each with symptoms and signs, although some symptoms may be present in more than one type. In addition to the three main categories, there are several rarer types of neurofibromatosis and other similar yet distinct genetic disorders.

The severity of neurofibromatosis can vary from person to person, and different symptoms can be present even among family members with the same type of NF. Different organ systems may be affected, as well. Here are the three main types of this genetic disorder:

What is NF Type 1 (Neurofibromatosis Type I or NF Type One)?

The most common form of neurofibromatosis, NF type 1, is typically diagnosed in childhood before age 10. Sometimes, symptoms are present at birth or are noticed shortly after. Children are born with neurofibromatosis type 1, and symptoms may develop gradually over several years. There are typical signs and symptoms that vary in severity and may include:

  • Café au Lait Spots – Flat birthmarks darker than the surrounding skin color
  • Freckles in the Groin or Armpits – May appear in clusters by ages 3 to 5
  • Neurofibroma Growths on or Under the Skin – Bumps may increase in number and size as a child ages. They are typically benign but are associated with a rare cancer and must be evaluated regularly
  • Small Growths on the Iris Called Lisch Nodules – Harmless and generally do not affect vision
  • Bone Deformities – Scoliosis or bowed legs from bone density deficiencies
  • Optic Tumors – Usually occur by age 3
  • Larger Head Size – Due to increased brain volume
  • Learning Disabilities – Mild impaired thinking skills, ADHD or speech delays
  • Short Stature – Children with NF type 1 are often below average in height
  • Increased Risk of Breast Cancer – Women with NF type 1 should be screened earlier and should remind their physicians of this increased risk in women under age 50
  • Hypertension – High blood pressure resulting from tumors on the adrenal glands or narrowing of the renal arteries. Patients with NF type 1 should have regular blood pressure monitoring

What is NF 2 (Neurofibromatosis Type II or NF Type 2)?

NF 2 is much less common than NF 1. The symptoms of this genetic condition typically appear in the late teen or early adult years. It is caused by an inherited gene defect or a spontaneously mutated gene. Neurofibromatosis type 2 may sometimes show symptoms at birth, in which case further tests and interventions are recommended. It is important to note that blood tests for NF 2 are not always reliable due to the variety of genes that may be affected in spontaneous mutation cases.

Patients may initially seek treatment for hearing problems in both ears, which leads to diagnoses or testing for neurofibromatosis. These hearing and other issues are sometimes caused by benign tumors (acoustic neuromas or vestibular schwannomas) growing on the hearing, balance and other nerves in the brain. There is currently no cure for NF 2. Treatment involves monitoring and treating problems that may occur. Other symptoms of NF 2 include:

  • Gradual Hearing Loss
  • Tinnitus (Ringing or Buzzing in the Ears)
  • Balance Issues
  • Numbness In Arms and Legs
  • Headaches
  • Facial Drooping
  • Cataracts or Vision Problems
  • Seizures
  • Growth of Tumors Along Other Nerves

Mosaic NF 2

One-third of patients with NF 2 have a form of the disease called mosaic NF 2. The symptoms and signs of this form are milder and typically located in one area or on one side of the body. Also, these patients have a lower risk of having children with NF 2.

What is Schwannomatosis (Neurofibromatosis Type 3 or NF3)?

Schwannomatosis, sometimes called neurofibromatosis type 3 or NF 3, is the rarest of the three main types of neurofibromatosis and was identified in the 1990s. Typically diagnosed in early adulthood after age 20, it is a complex and distinct genetic disorder that causes tumors to develop on spinal, cranial and peripheral nerves. NF 3 does not have a clear inheritance pattern and usually develops in patients without a family history of the condition.

For some patients, pain is the only symptom of the disease. Unlike NF 2, neurofibromatosis type 3 rarely forms on the nerve that carries balance and sound information to the brain and usually doesn’t grow on both hearing nerves. Therefore, Schwannomatosis patients typically don’t have the same hearing loss as NF 2 patients. Symptoms include:

  • Chronic Pain – Anywhere on the body and sometimes disabling
  • Muscle Weakness and Numbness – Anywhere on the body
  • Multiple Schwannomas – Nerve sheath tumors
  • Abnormal Nerve Sensations – Caused by tumors pressing on nerves or damaged nerves

Dr. Weinberg is a neurofibromatosis skin expert. Please get in touch with our office to schedule a consultation for the treatment of skin tumors and related conditions.

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