Neurofibromatosis type 1 (NF1, von Recklinghausen disease)

What changes during this transition

Neurofibromatosis type 1 is the most common autosomal dominant tumor predisposition syndrome in humans — incidence ~1 in 3000 worldwide, the same prevalence as cystic fibrosis, and more common than most people realize. It's caused by germline mutations in NF1 (chromosome 17q11.2) encoding neurofibromin, a GTPase-activating protein for RAS; loss of neurofibromin produces constitutive RAS-MAPK pathway activation with downstream PI3K-AKT-mTOR crosstalk. About half of cases are inherited, half sporadic; the gene is fully penetrant by age 5, but expression varies dramatically even within families. The 2021 revised NIH/Legius diagnostic criteria require ≥2 of: ≥6 café-au-lait macules, ≥2 neurofibromas (or one plexiform), axillary/inguinal freckling (Crowe sign), optic pathway glioma, ≥2 Lisch nodules or choroidal abnormalities, a distinctive osseous lesion (sphenoid wing dysplasia, long-bone bowing/pseudoarthrosis), a first-degree relative meeting criteria, or a heterozygous pathogenic NF1 variant. Clinical manifestations span virtually every organ. Cutaneous: café-au-lait macules, axillary/inguinal freckling, cutaneous neurofibromas in ~95% by adulthood (cosmetic burden plus occasional symptomatic lesions), and Lisch nodules. Neurofibromas come in three forms — cutaneous (discrete, dermal), subcutaneous (palpable, deep), and plexiform (often congenital, large, infiltrative, in ~30-50% of patients) — and plexiform lesions carry an ~8-13% lifetime risk of malignant transformation to MPNST (malignant peripheral nerve sheath tumor), the leading cause of NF1-adult mortality. New pain, rapid growth, and PET-avidity are the red flags. CNS: optic pathway gliomas in ~15-20% of pediatric patients (usually indolent, surveilled by symptom-triggered MRI; vision loss is the treatment trigger), other low-grade gliomas, learning disabilities + ADHD + autism-spectrum features in the recognized NF1 cognitive/behavioral phenotype, and ~5% seizure burden plus cerebrovascular dysplasia (Moyamoya-like). Skeletal: sphenoid wing dysplasia, tibial pseudoarthrosis, scoliosis, short stature, osteopenia. Endocrine: short stature, precocious puberty (especially with optic pathway gliomas), rare pheochromocytoma (~0.1-5.7%), GIST, and pediatric JMML. Vascular: NF1 vasculopathy → renal artery stenosis → hypertension (~25% of patients carry hypertension, and the workup must include renal artery imaging + plasma metanephrines for pheochromocytoma). Cancer risk beyond MPNST: breast cancer in women under 50 (2-5x elevated), GIST, JMML, optic pathway gliomas. Surveillance per Stewart 2018 / 2021 consensus and Children's Tumor Foundation guidance: annual clinical exam covering dermatologic, ophthalmologic, neurologic, blood pressure, growth and puberty assessment; whole-body MRI for plexiform neurofibroma burden in high-risk patients; brain MRI on visual or neurologic symptoms; developmental and educational assessment for learning disabilities; age-tiered cancer surveillance. Standard of care offers no cure for the underlying NF1 mutation; surgical management addresses symptomatic neurofibromas. The MEK inhibitor era opened in April 2020 with FDA approval of selumetinib (Koselugo) for pediatric NF1 with inoperable plexiform neurofibromas — the first FDA-approved targeted therapy for NF1, with ~70% objective response in pediatric NF1-PN — and extended in February 2025 with FDA approval of mirdametinib (Gomekli) for adults and pediatric patients ≥2 years with NF1-PN (a broader indication than selumetinib). Other MEK inhibitors (trametinib, binimetinib) remain in trial; imatinib has selected use; bevacizumab is used for select optic pathway glioma cases; MPNST is managed surgically with radiation. Cannabidiol is in emerging NF1 trials. The Children's Tumor Foundation, NF Network, and International Federation of Neurofibromatosis Foundations carry the patient-advocacy ecosystem. The editorial substrate framing for this page is sharp. NF1 is a constitutive RAS-MAPK pathway disease with PI3K-AKT-mTOR crosstalk, and the peptides users most commonly ask about — BPC-157 (angiogenic), GH/IGF-1 axis stimulants like CJC-1295 + tesamorelin + ipamorelin (drive IGF-1R/PI3K-AKT-mTOR), general-aging supplements like NMN — either push pathways in the wrong direction for a tumor predisposition syndrome or answer a different question than the one NF1 patients need answered. Tesamorelin's label contraindicates active malignancy, which is the load-bearing FDA-recognized caution for any patient with lifetime tumor predisposition. The clinical answer here is not a peptide protocol; it's NF1 multidisciplinary care, surveillance imaging, and access to the MEK inhibitor pathway when plexiform neurofibroma burden warrants it. This page exists so /ask can answer those questions honestly when users probe; it does not elevate any peptide as a discovery option for NF1. Sixty-seventh deliberate non-elevation.