Neurofibromatosis type 1
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.
What do I need to know?
NF1 is a condition that follows an pattern and affects nerve cell tissue, causing the growth of small tumours throughout the nervous system.
Features are present from 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 mutation; therefore, a family history of NF1 may not be present.
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 and/or axillary freckling
- multiple neurofibromas
Additional features can include:
- optic nerve glioma
- Lisch nodules (iris hamartomas)
- osseous lesions (eg sphenoid wing dysplasia, tibial pseudoarthrosis)
- increased risk of various cancers
- precocious puberty or delayed sexual development
- specific learning disabilities
- short stature
- hypertension that can be due to renal artery stenosis or phaeochromocytoma but is most often idiopathic.
Genetic testing can be helpful to make a diagnosis of NF1 where there are insufficient features present to make a clinical diagnosis. An example is a child with multiple café au lait spots and no other clinical features and no family history of NF1. It is also necessary for prenatal diagnosis and .
When should I refer?
Patients with NF1 (or a relevant family history) should be referred to genetics, paediatrics and/or neurology services.
- Douglas R.Stewart, Bruce R.Korf, Katherine L.Nathanson, David A .Stevenson, KalebYohay. Care of adults with neurofibromatosis type 1: a clinical practice resource of the American College of Medical Genetics and Genomics (ACMG). Genetics in Medicine 20(7), July 2018, Pages 671-682.
Resource for general practitioners