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Background: Neurofibromatosis 1 (NF1) is one of the most common inherited disorders characterized by mutations in the tumour suppressor gene NF1. Its clinical manifestations are highly variable and unpredictable. A specific NF1 mutation does not predict the severity or complications of the disease. Objective: The objective of this study was to build an empirical classification scheme without any a priori hypotheses to identify the underlying NF1 subtypes that best explain the observed heterogeneity. Methods: We performed latent class analysis (LCA) of 1351 consecutive NF1 patients aged >17 years seen between 2002 and 2014. Data and phenotypic features were collected prospectively on a standardized form. Results: The median age was 36.8 (17–81) years. A three‐class model showed the best fit: 706 (52%) belonged to the LC1 'Cutaneous neurofibromas' class having preferentially cutaneous neurofibromas (99%), plexiform neurofibromas (63%) and blue‐red macules (29%); 593 (44%) belonged to the LC2 'Subcutaneous neurofibromas' class characterized by the presence of at least 10 subcutaneous neurofibromas (21%) and a familial form (77%) and 52 (4%) belonged to the LC3 'Dysmorphic phenotype' class characterized by dysmorphic features (78%) and learning difficulties (87%). Patients in LC1 had a higher likelihood of developing scoliosis (RR = 1.7, 95% confidence interval (CI) [1.2–2.4]). Patients in LC2 were more likely to be men (RR = 1.4, 95% CI [1.1–1.7]). Patients in LC3 were at higher risk of having an optic pathway glioma (RR = 4.8, 95% CI [1.9–11.8]) and epilepsy (RR = 4.5, 95% CI [1.8–11.6]). Conclusion: Our findings invite the performance of a larger cohort study to test whether the various latent classes reflect different underlying genetic modifiers of these phenotypic traits. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 is a relatively common genetic disease, with a prevalence ranging between 1/3000 and 1/6000 people worldwide. The disease affects multiple systems with cutaneous, neurologic, and orthopedic as major manifestations which lead to significant morbidity or mortality. Indeed, NF1 patients are at an increased risk of malignancy and have a life expectancy about 10-15 years shorter than the general population. The mainstay of management of NF1 is a patient-centered longitudinal care with age-specific monitoring of clinical manifestations, aiming at the early recognition and symptomatic treatment of complications as they occur. Protocole national de diagnostic et de soins (PNDS) are mandatory French clinical practice guidelines for rare diseases required by the French national plan for rare diseases. Their purpose is to provide health care professionals with guidance regarding the optimal diagnostic and therapeutic management of patients affected with a rare disease; and thus, harmonizing their management nationwide. PNDS are usually developed through a critical literature review and a multidisciplinary expert consensus. The purpose of this article is to present the French guidelines on NF1, making them even more available to the international medical community. We further dwelled on the emerging new evidence that might have therapeutic potential or a strong impact on NF1 management in the coming feature. Given the complexity of the disease, the management of children and adults with NF1 entails the full complement healthcare providers and communication among the various specialties. [ABSTRACT FROM AUTHOR]