# Neurofibromatosis type 1

Source: https://onco.cc/terms/neurofibromatosis-type-1/  
OnCo record `neurofibromatosis-type-1` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Neurofibromatosis type 1 is an inherited condition, affecting about one in 2,000 to 2,500 babies, that causes nerve tumours called neurofibromas and raises the risk of some cancers. Regular check-ups find problems early, and two tablets now shrink the large plexiform neurofibromas that cannot be removed by surgery.

## Summary

Autosomal dominant, caused by a pathogenic variant in NF1; about half of people inherit it and half have a new variant (ERN GENTURIS, Carton 2023). It predisposes to benign and malignant tumours: plexiform and cutaneous neurofibromas, optic pathway glioma, malignant peripheral nerve sheath tumour (MPNST), phaeochromocytoma, paraganglioma, gastrointestinal stromal tumour, breast cancer, glomus tumours of the digits and juvenile myelomonocytic leukaemia.

The 2023 ERN GENTURIS guideline (modified Delphi, NF1 experts and patient representatives) advises annual assessment of children up to ten and at least two-yearly after that, with yearly visual assessment for optic pathway glioma up to age eight; a whole-body MRI at the transition to adulthood to measure internal plexiform tumour burden as a predictor of MPNST risk; clinical assessment of adults at least every three years; urgent resection without watchful waiting for MPNST; and annual breast MRI from as soon after 30 as the local system allows, to age 50. The AACR 2017 paediatric recommendations advised against routine MRI in children without visual symptoms; the 2024 AACR update harmonised paediatric surveillance across NF1 and the other RASopathies.

The MEK inhibitors selumetinib (US 2020, children; extended to adults in 2025) and mirdametinib (US and EU 2025, adults and children) are approved for symptomatic plexiform neurofibromas that cannot be removed.

## Fields

- Kind: Term
- Last checked: 2026-11-04
- Also known as: neurofibromatosis type I; NF1 syndrome; NF1 neurofibromatosis
- Tags: gap-fill; hereditary

## Notes

- NHS England genomic test directory: R222 (NF1 and SPRED1). Orphanet ORPHA:636.
- Where the guideline gives a figure it is a recommendation strength, not an outcome: the breast MRI and whole-body MRI advice are graded moderate and weak respectively in the ERN GENTURIS table.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Neurofibromatosis_type_I
- Carton, EClinicalMedicine 2023: ERN GENTURIS tumour surveillance guidelines for neurofibromatosis type 1: https://doi.org/10.1016/j.eclinm.2022.101818
- Perrino, Clin Cancer Res 2024: paediatric cancer surveillance in NF1 and the RASopathies (AACR update): https://doi.org/10.1158/1078-0432.ccr-24-1611
- Evans, Clin Cancer Res 2017: cancer and CNS tumour surveillance in paediatric NF1 (AACR): https://doi.org/10.1158/1078-0432.ccr-17-0589
- Orphanet ORPHA:636: https://www.orpha.net/en/disease/detail/636
- NHS England National Genomic Test Directory, rare and inherited disease, version 9 (spreadsheet): https://www.england.nhs.uk/wp-content/uploads/2018/08/rare-and-inherited-disease-national-genomics-test-directory-v9.xlsx

## Connected records

- cancers: [Malignant peripheral nerve sheath tumour (MPNST)](https://onco.cc/cancers/malignant-peripheral-nerve-sheath-tumour/), [Optic pathway glioma](https://onco.cc/cancers/optic-pathway-glioma/)
- technologies: [Germline (hereditary) testing](https://onco.cc/technologies/germline-testing/), [Whole-body MRI](https://onco.cc/technologies/whole-body-mri/)
- targets: [NF1 (neurofibromin)](https://onco.cc/targets/nf1/)
- drugs: [Mirdametinib](https://onco.cc/drugs/mirdametinib/), [Selumetinib](https://onco.cc/drugs/selumetinib/)
- terms: [Hereditary cancer syndromes](https://onco.cc/terms/hereditary-cancer-syndromes/)

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