Clinical features: The diagnosis of NF1 is made on clinical findings. Strict diagnostic criteria have been established and should always be used when assessing individuals. An individual with NF1 has two or more of the following features:
About half the individuals with NF1 have a learning disability, although this is usually mild. Once the diagnosis is made it is important to instigate surveillance for some of the complications that may occur.
Incidence: NF1 is one of the most common inherited conditions, with a prevalence of 1 in 3000 individuals.
Inheritance : Autosomal dominant, with extremely variable expression. About 50% of individuals with NF1 have an affected parent, the remaining 50% have the condition as the result of a new mutation.
Gene: NF1 is caused by mutations in the neurofibromin (NF1) gene on chromosome 17. More than 500 mutations have been described, no common mutation existing in any population. DNA testing by direct mutation detection is available but is very complicated due to the large size of the gene and is usually reserved for very specific clinical situations. The mutation detection rate approaches 90%. Advice from the local clinical genetics service should be sought before investigations are undertaken.
Prenatal diagnosis: Rarely requested, but possible if the mutation is identified in affected family members. If a family is considering prenatal diagnosis, referral should be made to the local clinical genetics service prior to a pregnancy. This ensures family members are offered appropriate advice and investigations, to confirm whether or not prenatal diagnosis is possible.
Presymptomatic testing: It is recommended that first degree relatives of an individual with NF1 are clinically evaluated for signs of the condition.
UK Support Group: Neurofibromatosis Association Quayside House 38 High Street Kingston on Thames KT1 1HL Tel: 020 8439 1234 Web: www.nfauk.org
If you would like further information on Neurofibromatosis Type 1 please go to either:-
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