What is Neurofibromatosis?

Neurofibromatosis is a set of distinct genetic disorders that 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. Neurofibromatosis causes tumors to grow anywhere on or in the body. Neurofibromatosis (NF) has been classified into three distinct types: NF1, NF2 and Schwannomatosis. Rylie has been diagnosed with NF1.

Neurofibromatosis 1 (NF1), which is what Rylie has been diagnosed with, is also known as von Recklinghausen NF or Peripheral NF. NF1 occurs in only 1 of every 3,000 births. Multiple cafe-au-lait spots and neurofibromas on or under the skin characterize NF1. NF1 and NF2 are called autosomal dominant genetic disorders. Half of all cases are inherited from a parent who has NF1 or NF2, the other half of all cases are not inherited but the result of a new or spontaneous mutation (change) in the sperm or egg cell. Rylie’s case has been confirmed as a spontaneous mutation. 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. 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. Thus, a total of 2 children in 7,000 or 1 in 3,500 are born with NF1.

NF is an extremely variable disorder. The severity of NF ranges from extremely mild cases in which the only signs of the disorder in adulthood may be multiple café-au-lait spots and a few dermal neurofibromas, to more severe cases in which one or more serious complications may develop. There is no way to predict who will have a mild case and who will develop serious complications. The majority of people with NF (probably 60%) have mild forms of the disorder. Another 20% have correctable problems and another 20% have serious and persistent problems. Many of the serious problems in NF are evident at birth or develop prior to adolescence. These may include congenital defects of the bone, scoliosis, optic glioma and neurological impairment leading to learning disability or mental retardation. People with NF who have reached adulthood without having these problems are unlikely to develop them.

To learn more about NF visit the Children’s Tumor Foundation’s website at www.ctf.org.