What is Neurofibromatosis?
Neurofibromatosis is the name given to a set of genetic disorders that cause tumours to grow along various types of nerves and can affect development of bones and skin. Neurofibromatosis can cause tumours to grow anywhere in or on the body.
Neurofibromatosis 1 (Nf1): occurs in around 1:3000 births, it 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, tumours may develop in the brain, on cranial nerves, or on the spinal cord. About 50% of people with NF1 also have learning disabilities.
Neurofibromatosis 2 (Nf2): is much rarer and occurs in 1:25,000 births and is characterized by multiple tumours on the cranial and spinal nerves, and by other lesions of the brain and spinal cord... Hearing loss beginning in the teens or early twenties is generally the first symptom.
Schwannomatosis: a rare form of Nf and appears to affect around 1:40,000. It is less well understood than Nf1 and Nf2 and its features may vary greatly between patients.
You may hear Nf1 called an autosomal dominant disorder. Half of all cases are inherited from a parent who has the condition and half are the result of a new or spontaneous mutation (a change in the sperm or egg cell) l. Each child of a parent with Nf1 a 50% chance of inheriting the gene and developing the condition. . The type of Nf1 inherited by a 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). However, the severity and the kind of manifestations may differ from person to person even within the same family.
When a parent has Nf2, there is a 50% chance with each pregnancy for the child to receive the Nf1 gene, and a 50% chance for the child to receive two unaffected genes and to be free of Nf1. The child with NF1, as a result of a new mutation, does have the 50-50 chance of passing the Nf1 gene on to his or her children.
Unaffected parents who have a child born with Nf1 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.
Nf1 is caused by a genetic defect or 'spelling mistake' on chromosome 17.