NF1 is caused by pathogenic variants in the NF1 gene (ClinGen validity: DEFINITIVE), which encodes neurofibromin, a GTPase-activating protein that functions as a tumor suppressor by negatively regulating the RAS signaling pathway. The condition is inherited in an autosomal dominant manner, with nearly complete penetrance after childhood per GeneReviews; clinical expressivity is highly variable. Approximately half of NF1 cases arise from de novo pathogenic variants, consistent with the condition's high mutation rate at the NF1 locus. NF1 pathogenic variants include point mutations, small insertions and deletions, and larger intragenic deletions; recognized subtypes include NF1 due to NF1 mutation or intragenic deletion (MONDO:0018208) and chromosome 17q11.2 deletion syndrome (1.4Mb, MONDO:0013357), the latter associated with more severe manifestations. Familial spinal neurofibromatosis (MONDO:0008078) is an additional recognized subtype.

Clinical diagnosis of NF1 uses established NIH diagnostic criteria; per GeneReviews, criteria include any one of: six or more CALMs of appropriate size (≥5 mm prepubertal, ≥15 mm postpubertal), axillary or inguinal freckling, two or more neurofibromas or one plexiform neurofibroma, optic pathway glioma, two or more Lisch nodules or choroidal abnormalities, a distinctive osseous lesion, or an NF1 pathogenic variant in a first-degree relative. Molecular genetic testing by NF1 gene sequencing and deletion/duplication analysis confirms the diagnosis in individuals not meeting clinical criteria or in those with ambiguous presentations. Ophthalmologic evaluation including slit-lamp examination identifies Lisch nodules and monitors for optic pathway involvement. MRI is used for assessment of internal tumors, including plexiform neurofibromas and optic gliomas. Blood pressure monitoring evaluates for renovascular hypertension, a recognized NF1 complication.

Annual comprehensive clinical examinations form the cornerstone of NF1 management, targeting early detection of complications. Selumetinib (Koselugo), a MEK1/2 inhibitor, is used for inoperable plexiform neurofibromas in pediatric patients and represents a targeted pharmacologic therapy for this NF1 complication. Symptomatic neurofibromas may be addressed with surgical removal. Ophthalmologic evaluation including slit-lamp examination monitors for Lisch nodules and optic pathway glioma. MRI surveillance is performed for plexiform neurofibromas and optic gliomas at intervals guided by clinical context. Blood pressure monitoring is conducted for renovascular hypertension. Educational support and individualized academic planning address specific learning disabilities, which affect approximately half of individuals with NF1. Per GeneReviews, referral to a neurofibromatosis clinic staffed by multidisciplinary specialists with NF1 expertise may benefit many affected individuals. Management guidelines for children with NF1 have been published by the American Academy of Pediatrics and American College of Medical Genetics and Genomics.

Per GeneReviews, NF1 follows an extremely variable clinical course; severity and progression differ across individuals and even among family members with the same pathogenic variant. Most individuals with NF1 live productive lives, though the condition imposes a range of medical, educational, and psychosocial burdens. Optic pathway gliomas, while more frequent than in the general population, most often follow a benign course. The most serious oncologic complication is malignant peripheral nerve sheath tumors, which arise predominantly in individuals with large or numerous plexiform neurofibromas and carry a significantly worse prognosis than the same tumors in the general population. Women with NF1 face elevated breast cancer risk and increased pregnancy complications. NF1-associated vasculopathy poses risk of stroke in affected children and young adults. GeneReviews notes that elevated mortality relative to the general population reflects these serious complications; specific survival statistics are not provided in this packet.

Active clinical trials are investigating NF1 therapies and natural history (source: ClinicalTrials.gov). NCT03975829: 'Pediatric Long-Term Follow-up and Rollover Study' — Phase 4, ACTIVE_NOT_RECRUITING, sponsored by Novartis Pharmaceuticals (start: November 2019; estimated completion: November 2026). NCT05101148: 'Phase I Study to Assess the Effect of Food on the PK and Gastrointestinal Tolerability of Selumetinib in Adolescent Children With NF1 Related Plexiform Neurofibromas' — Phase 1, ACTIVE_NOT_RECRUITING, sponsored by AstraZeneca (start: July 2021; estimated completion: April 2028). NCT04590235: 'A Study of Selumetinib in Chinese Paediatric and Adult Subjects With NF1 and Inoperable Plexiform Neurofibromas' — Phase 1, ACTIVE_NOT_RECRUITING, sponsored by AstraZeneca (start: December 2020; estimated completion: August 2026). NCT04750928: 'CDK4/6 Inhibitor Abemaciclib for NF1 Related Atypical Neurofibromas' — Phase 1, RECRUITING, sponsored by National Cancer Institute (NCI) (start: November 2021; estimated completion: December 2029).