 |
 |
 |
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. It also leads to developmental abnormalities. For example, individuals with NF have a higher incidence of learning disabilities.
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.
Types Of Neurofibromatosis
Neurofibromatosis (NF) has been classified into two distinct types: NF1 and NF2.
Neurofibromatosis 1 (NF1), also known as von Recklinghausen NF or Peripheral NF, occurring in 1:4,000 births, is 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 1:40,000 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.
Genetics of the Neurofibromatoses (NF)
Both forms of NF are autosomal dominant genetic disorders which may 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 a parent with NF 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 (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), although the severity and the kind of manifestations may differ from person to person within a family.
Two different methods are applied in the genetic diagnosis of NF1. First, a "Multiplex Ligation-dependent Probe Amplifikation" (MLPA) is performed in order to detect major insertions/deletions. Second, a complete sequencing of all 57 exons of the NF1 gene is performed.
