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The diagnosis of neurofibromatosis type 1 (NF1) is usually made on clinical grounds.
While genetic testing is not needed to confirm a diagnosis, confirmation of a gene variants can be useful information for family members and family planning.1,2
What do I need to know?
NF1 is a condition that follows an Autosomal dominant inheritance pattern and affects nerve cell tissue, causing the growth of small tumours throughout the nervous system.
Symptoms usually appear during childhood and may become more pronounced during puberty, pregnancy and when hormonal changes take place. The severity of the condition can vary greatly, even within a family.
NF1 may be inherited, but up to 50% of cases are caused by a de novo mutation; therefore, family history may not be present.2
The diagnosis of NF1 is made on the basis of presence of specific physical findings. Characteristic features of NF1 include:
- multiple café-au-lait spots
- inguinal or axillary freckling
- multiple neurofibromas.
Additional features can include:1,2
- optic glioma
- Lisch nodules (iris hamartomas)
- osseous lesions (eg sphenoid dysplasia)
- increased risk of various cancers
- precocious puberty or delayed sexual development
- specific learning disabilities
- short stature
- renal artery stenosis.
While genetic testing is not needed to confirm a diagnosis, confirmation of a gene variant can provide useful information for family members or family planning (ie prenatal diagnosis, pre-implantation genetic diagnosis ).1
When should I refer?
Patients with NF1 (or a relevant family history) should be referred to genetics, paediatrics or neurology services.
Resource for general practitioners
BMJ Best Practice, Type 1 neurofibromatosis
Resources for patients
Centre for Genetics Education, Fact sheet 45: Neurofibromatosis type 1
National Library of Medicine (US), Neurofibromatosis type 1