If a parent has Neurofibromatosis Type II (NF2) that has been confirmed through genetic testing, then their first degree relatives, which include their children and their siblings, all have a 50% chance of also carrying the same NF2 mutation. The exception to this is when a person has a mosaic form of NF2, which is also called segmental NF2. Mosaic NF2 means a person has a mutation in the NF2 gene, but it is not present in every single cell of their body, so it may not be present in the egg or the sperm. If a person’s NF2 mutation is not present in their germ cells (egg or sperm), then they cannot pass that mutation onto their children. It is not possible to test all egg and sperm to know what this risk is. So patients in this situation are counseled that the risk of having a child with NF2 is as high as 50% but it could be lower or even zero.
Also, it is well known that NF2 can have a wide range of symptoms and a wide range of ages when symptoms start. Symptoms like cataracts can be present at birth, where there are other cases where a patient doesn’t show symptoms until 70. However, on average, most people show some feature between 18 and 24. Given this age range, and because screening for NF2 tumors starts in childhood, genetic testing for familial mutations is recommended at a younger age. Also, there is a lot of variability in disease presentation, even between members of the same family.
To learn more about genetic testing and who else may be at risk to have NF2 in a family it can be helpful to talk with a genetics professional. A medical geneticist can be found by asking your doctor for a referral or looking on the American College of Medical Geneticists website. Genetic counselors can be found on the National Society of Genetic Counselors website.
