What Are the 3 Types of Neurofibromatosis?

Medically Reviewed on 10/27/2021
Neurofibromatosis
The 3 types of neurofibromatosis include neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis (SWN).

A neurofibromatosis is a group of genetic conditions that causes tumor formation on the nerves, brain, spinal cord, and skin. The tumors are generally noncancerous (benign) although some tumors may develop cancerous changes (malignancies).

The three types of neurofibromatosis include:

  1. Neurofibromatosis type 1 (NF1):
    • Also called von Recklinghausen disease, it is the most common type of neurofibromatosis that affects 1 in 3,000 births. It is generally diagnosed during childhood.
    • Humans have 23 pairs of chromosomes that store genetic information: 22 pairs are called autosomal chromosomes, and one pair is called sex chromosomes.
      • NF1 is an autosomal dominant condition.
      • Autosomal means that the defective gene is present on autosomal chromosomes, and dominant means that the disease will manifest even if a single defective gene is present.
      • NF1 is caused by a defect in the NF1 gene that codes for a protein called neurofibromin.
  2. Neurofibromatosis type 2 (NF2):
    • Also called central neurofibromatosis or bilateral acoustic neurofibromatosis and affects about 1 in 25,000 births.
    • It is caused by a defective NF2 gene that codes for a protein called the intracellular membrane-associated protein neurofibromin-2.
    • The condition is generally diagnosed during teenage or soon after puberty.
  3. Schwannomatosis (SWN):
    • The rarest form of neurofibromatosis, which may be caused by a defect in the SMARCB or LZTR1 genes.
    • In some people, however, the exact cause of SWN may be unknown.
    • SWN is generally diagnosed when an individual is in their 20s.

What are the signs of neurofibromatosis?

Signs and symptoms of neurofibromatosis may vary from person to person.

Signs and symptoms of neurofibromatosis type 1

  • Symptoms begin soon after birth or early childhood
  • Café au lait spots (light brown spots measuring 5 to 15 mm; six or more in number)
  • Freckling of the arms and groin region
  • Multiple neurofibromas (small, painless tumors seen as nodular swellings or felt under the skin)
  • Vision problems (seen in case of optic gliomas or tumors that affect the nerves of the eyes)
  • Plexiform neurofibroma (a large, disfiguring tumor formed due to multiple nerve involvement)
  • Lisch nodules (small tumors that affect the iris [colored part of the eye], seen on eye examination)
  • Weakness
  • Learning problems and delayed milestones including delayed speech or walking
  • Macrocephaly (the head appears larger than normal)
  • High blood pressure
  • Bone abnormalities such as bowing of the shinbone or abnormal curvature of the spine

Signs and symptoms of neurofibromatosis type 2

Signs and symptoms of schwannomatosis

  • Symptoms start in adulthood (the 20s)
  • Chronic (long term) pain that affects any part of the body
  • Muscle weakness
  • Tingling, numbness, or weakness in the fingers and toes
  • Tumors limited to a particular part of the body such as the arm, leg, or a particular spinal region

Can neurofibromatosis be cured?

Presently, there is no cure for any type of neurofibromatosis. Conditions, however, can be treated and managed for an improved quality of life. Treatment generally focuses on managing symptoms (such as pain, headache, and seizures) and preventing complications. 

Generally, a multidisciplinary team is required, which consists of:

  • Internists
  • Neurologists
  • Orthopedic surgeons
  • Ophthalmologists
  • Ear, nose, and throat surgeons
  • Neurosurgeons

The U.S. Food and Drug Administration approved the drug selumetinib (Koselugo) in April 2020 for managing neurofibromatosis type 1 in children who are two years of age and older. This drug prevents the growth of tumor cells.

Various clinical trials are underway to develop improved treatment options for neurofibromatosis.

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Medically Reviewed on 10/27/2021
References
Image Source: chiewr / Getty Images

https://www.uptodate.com/contents/the-genodermatoses-an-overview?search=neurofibromatosis&source=search_result&selectedTitle=4~150&usage_type=default&display_rank=4#H29839266

https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Neurofibromatosis-Fact-Sheet