The neurofibromatoses (NF) are a set of genetic disorders which cause tumors to grow along various types of nerves and, in addition, can affect the development of non-nervous tissues such as bones and skin. NF causes tumors to grow anywhere on or in the body. A variety of terms are used to refer to NF.
In 1882, NF was first delineated in the medical literature by Dr. Friedrich von Recklinghausen and was so known as Von Recklinghausen's Disease for many years.
Phakomatosis, from the Greek word "phakos" (meaning birthmark), refers to several disorders, including NF, characterized by birthmarks.
Neurocutaneous Disorder refers to any one of several disorders, of which NF is the most common, which affect the skin and the nervous system.
Neurofibromatosis (NF) has been classified into three distinct types: NF1, NF2 and Schwannomatosis.
Neurofibromatosis 1 (NF1): also known as von Recklinghausen NF or Peripheral NF. Occurring in 1:3,000 births, web characterized by multiple cafe-au-lait spots and neurofibromas on or under the skin. Enlargement and deformation of bones and curvature of the spine (scoliosis) may also occur. Occasionally, tumors may develop in the brain, on cranial nerves, or on the spinal cord. About 50% of people with NF also have learning disabilities.
Neurofibromatosis 2 (NF2): also known as Bilateral Acoustic NF (BAN), is much rarer occurring in 1:25,000 births. NF2 is characterized by multiple tumors on the cranial and spinal nerves, and by other lesions of the brain and spinal cord. Tumors affecting both of the auditory nerves are the hallmark. Hearing loss beginning in the teens or early twenties is generally the first symptom.
Schwannomatosis: a rare form of NF that has only recently been recognized and appears to affect around 1:40,000 individuals. It is less well understood than NF1 and NF2, and features may vary greatly between patients.
NF1 and NF2 are called autosomal dominant genetic disorders. Half of all cases are inherited from a parent who has NF1 or NF2; half of all cases are not inherited but the result of a new or spontaneous mutation (change) in the sperm or egg cell. Each child of a parent with NF1 or NF2 has a 50% chance of inheriting the gene and developing NF1 or NF2.
The type of NF inherited by the child is always the same as that of the affected parent (i.e. if the parent has NF1, each child is at 50% risk for NF1. If the parent has NF2, each child has a 50% chance to inherit NF2). However, the severity and the kind of manifestations may differ from person to person within a family. When a parent has NF1 or NF2, there is a 50% chance with each pregnancy for the child to receive the NF1 or NF2 gene, and a 50% chance for the child to receive two unaffected genes and to be free of NF1 or NF2.
The child with NF1 or NF2, as a result of a new mutation, does have the 50-50 chance of passing the NF1 or NF2 gene on to his or her children. Unaffected parents who have a child born with NF1 or NF2 because of a spontaneous mutation do not have a 50-50 risk in future pregnancies. Their chance for another child with NF1 is about the same as that of any couple in the general population, that is, one chance in 7,000. One additional birth in every 7,000 results in a child who has inherited NF1 from a parent with the disorder. Thus, a total of 2 children in 7,000 or 1 in 3,500 are born with NF1.
NF has been classified into three distinct types; NF1, NF2 and Schwannomatosis. They are caused by different genes, located on different chromosomes.
♦NF1 is not a rare disorder, it is the most common neurological disorder caused by a single gene.
♦NF1 is the more common form of NF, occurring in 1:3,000 births throughout the world.
♦NF2 is a rarer type, occurring in 1:25,000 people worldwide.
♦While today there is no consensus, studies indicate that Schwannomatosis occurs in 1:40,000 people, similar to NF2.
♦The Neurofibromatoses are genetically-determined disorders which affect more than 100,000 Americans; this makes NF more prevalent than Cystic Fibrosis, hereditary Muscular Dystrophy, Huntington's Disease and Tay Sachs combined.
♦All forms of NF are autosomal dominant genetic disorders which can be inherited from a parent who has NF or may be the result of a new or "spontaneous mutation" (change) in the sperm or egg cell.
♦Each child of an affected parent has a 50% chance of inheriting the gene and developing NF. The type of NF inherited by the child is always the same as that of the affected parent, although the severity of the manifestations may differ from person to person within a family.
♦NF is worldwide in distribution and affects both sexes equally and has no particular racial, geographic or ethnic distribution. Therefore, NF can appear in any family.
♦Although most cases of NF1 are mild to moderate, NF1 can lead to disfigurement; blindness; skeletal abnormalities; dermal, brain and spinal tumors; loss of limbs; malignancies; and learning disabilities.
♦NF1 also has a connection to developmental problems, especially learning disabilities, which are five times more common in the NF1 population than in the general population.
♦The distinguishing feature of NF2 is tumors that grow on the eighth cranial nerve in both ears, commonly causing deafness and severe balance problems.
♦NF2 brings on increased risk of other types of nervous system tumors as well.
♦NF2 can also cause severe vision problems, including cataracts, retinal abnormalities and orbital tumors.
♦Accordingly, NF research may benefit an additional 100 million Americans (i.e. 65 million with cancer and 35 million with learning disabilities).
♦NF is not the "Elephant Man's Disease," although it was at one time believed to be. Scientists now believe that John Merrick, the so-called "Elephant Man," had Proteus Syndrome, an entirely different disorder.
♦NF research began eighteen years ago by the Children's Tumor Foundation, has been enormously productive ever since.