NF1 is a progressive disorder, which means most symptoms will worsen over time, although a small number of people may have symptoms that remain constant. It isn’t possible to predict the course of an individual’s disorder. In general, most people with NF1 will develop mild to moderate symptoms. Most people with NF1 have a normal life expectancy. Neurofibromas on or under the skin can increase with age and cause cosmetic and psychological issues.
Symptoms, particularly the most common skin abnormalities-café-au-lait spots, neurofibromas, Lisch nodules, and freckling in the armpit and groin-are often evident at birth or shortly afterwards, and almost always by the time a child is 10 years old. Because many features of these disorders are age dependent, a definitive diagnosis may take several years.
Many children with NF1 have larger than normal head circumference and are shorter than average. Hydrocephalus, the abnormal buildup of fluid in the brain, is a possible complication of the disorder. Headache and epilepsy are also more likely in individuals with NF1 than in the healthy population. Cardiovascular complications associated with NF1 include congenital heart defects, high blood pressure (hypertension), and constricted, blocked, or damaged blood vessels (vasculopathy). Children with NF1 may have poor language and visual-spatial skills, and perform less well on academic achievement tests, including those that measure reading, spelling, and math skills. Learning disabilities, such as attention deficit hyperactivity disorder (ADHD), are common in children with NF1. An estimated 3 to 5 percent of tumors may become cancerous, requiring aggressive treatment. These tumors are called malignant peripheral nerve sheath tumors.
To diagnose NF1, a doctor looks for two or more of the following:
- six or more light brown spots on the skin (often called “café-au-lait” spots), measuring more than 5 millimeters in diameter in children or more than 15 millimeters across in adolescents and adults
- two or more neurofibromas, or one plexiform neurofibroma (a neurofibroma that involves many nerves)
- freckling in the area of the armpit or the groin
- two or more growths on the iris of the eye (known as Lisch nodules or iris hamartomas)
- a tumor on the optic nerve (called an optic nerve glioma)
- abnormal development of the spine (scoliosis), the temple (sphenoid) bone of the skull, or the tibia (one of the long bones of the shin)
- a parent, sibling, or child with NF1
NF1 is the most common neurofibromatosis, occurring in 1 in 3,000 to 4,000 individuals in the United States. Although many affected people inherit the disorder, between 30 and 50 percent of new cases result from a spontaneous genetic mutation of unknown cause. Once this mutation has taken place, the mutant gene can be passed to succeeding generations.
Why these tumors occur still isn’t completely known, but it appears to be related mainly to mutations in genes that play key roles in suppressing cell growth in the nervous system. These mutations keep the genes—identified as NF1, NF2 and SMARCB1/INI1—from making normal proteins that control cell production. Without the normal function of these proteins, cells multiply out of control and form tumors.
The most common nerve-associated tumors in NF1 are neurofibromas (tumors of the peripheral nerves), whereas schwannomas (tumors that begin in Schwann cells that help form the myelin sheath) are most common in NF2 and schwannomatosis. Most tumors are benign, although occasionally they may become cancerous.
Scientists have classified the disorders as neurofibromatosis type 1 (NF1, also called von Recklinghaus disease), neurofibromatosis type 2 (NF2), and a type that was once considered to be a variation of NF2 but is now called schwannomatosis. An estimated 100,000 Americans have a neurofibromatosis disorder, which occurs in both sexes and in all races and ethnic groups.
Neurofibromatosis is a group of three genetically distinct disorders that cause tumors to grow in the nervous system. Tumors begin in the supporting cells that make up the nerve and the myelin sheath (the thin membrane that envelops and protects the nerves), rather than the cells that actually transmit information. The type of tumor that develops depends on the type of supporting cells involved.
ABOUT NEUROFIBROMATOSIS (NF):*
• Neurofibromatosis, or NF, is a common, yet under- recognized genetic disorder that can cause tumors to grow on nerves throughout the body.
• NF is more prevalent than cystic fibrosis, Duchenne muscular dystrophy, and Huntington’s disease combined.
• NF occurs in one in every 3,000 people and affects millions worldwide.
• NF can lead to blindness, bone abnormalities, cancer, deafness, disfigurement, learning disabilities, and excruciating and disabling pain.
• NF can arise in any family regardless of race or ethnic origin. Roughly half of all cases arise in families with no history of the disorder.
• NF has three distinct forms, NF1, NF2, and schwannomatosis.
• NF research is shedding new light on several forms of cancer, brain tumors, bone abnormalities and learning disabilities, ultimately benefiting the broader community in addition to those with NF.
• Progress toward ending NF is being made every day. Because of Children’s Tumor Foundation funding, there are over 40 on-going NF-specific clinical trials in existence, and 44 NF Clinics nationwide.
* Above information was provided by the Children’s Tumor Foundation (CTF.org)