Genetics of NF1 & NF2

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.