Neurofibromatosis type 1 (NF1) is usually diagnosed by checking for the characteristic symptoms of the condition.
A confident diagnosis can usually be made if two or more of the following symptoms are present:
It's usually easy to diagnose NF1 in adults and older children, but it can take several years for all the symptoms to develop in young children. As a result, it's not always possible to make a firm diagnosis before a child is five years old.
Further tests may be recommended to assess whether your child has developed additional symptoms or secondary conditions known to be associated with NF1. Some of these tests are described below:
If there's uncertainty about the diagnosis, your child can be tested to see whether they have the NF1 mutated gene. This involves extracting DNA from a sample of their blood and analysing it to check whether they've inherited the faulty gene.
However, the test isn't always completely reliable. Around 5% of children who test negative for the mutated gene still develop NF1.
Couples with a family history of NF1 who are thinking of having a baby can be referred to a genetics specialist for advice.
A genetic counsellor can help couples work through the decision-making process and explain possible alternatives, such as adoption or artificial insemination (where sperm taken from the man is inserted directly into his partner’s womb).
There are also a number of tests that can be carried out during pregnancy to check if a baby will develop NF1. These include:
However, these tests can't determine how severe the condition will be. Even if a parent is severely affected by the condition, it doesn't mean their children will be.
For couples at risk of having a child with NF1, pre-implantation genetic diagnosis (PGD) may be an option.
PGD involves using in-vitro fertilisation (IVF), where eggs are removed from a woman's ovaries before being fertilised with sperm in a laboratory. After a few days, the resulting embryos can be tested for NF1 and a maximum of two unaffected embryos are transferred into the uterus.
However, funding for PGD is decided on an individual basis. For example, you may be considered ineligible for PGD on the NHS if you already have unaffected children or if the chances of success are thought to be low. In these cases you can choose to fund PGD yourself, although it's likely to cost between £6,000 and £10,000.