Neurofibromatosis von Recklinghausen type 1 (NF1) is the most frequent disease from the group of neurocutaneous syndromes, resulting from disturbances of tissue differentiation (primarily neuroectoderm). NF1 has autosomal dominant inheritance, with a 40–50 % incidence of new mutations and prevalence in the population 1:3000–4000. The gene is localized on chromosome17 (17q11.2), its product neurofibromin reduces cell proliferation through acceleration of hydrolysis of the active GTP-Ras to inactive GDP-Ras and so plays a role of a negative growth regulator and tumor suppressor. Loss of neurofibromin in the Schwann cell leads to accelerated proliferation of this cell (together with influencing proliferation of fibroblasts and mastocytes) and to tumor generation. Diagnosis of NF1 is determined using the following diagnostic criteria: café au lait spots, axillar and/or inguinal freckling, neurofibromas and/or plexiform neurofibroma, optic glioma, Lisch nodules, characteristic bone lesions (sphenoidal dysplasia, anomaly of long bones), first-degree relative with a confirmed diagnosis of NF1. To make diagnosis of NF1, it is necessary to fulfill at least two diagnostic criteria. Among other typical clinical findings in NFl, there are hypersignal foci in T2-weighted brain MR images, microcephaly, scoliosis, small stature, specific developmental disorders of learning, disorders of attention and behavior, systemic hypertension with fibromuscular dysplasia of renal arteries. Endocrinologic disturbances arc less frequent, rarely, ischemic strokes occur when cerebral vasculature is affected. Neoplastic processes are usually benign, malignant transformation is described in 2–6 % of cases. Therapy is primarily symptomatic, in progressive lesions also surgical, in malignant tumors oncological. Regime and education precautions are significant in specific developmental disorders. Prenatal diagnostics is currently possible using indirect DNA analysis in informative families, direct DNA analysis is being developed.

        Key words: neurofibromatosis von Recklinghausen type 1, neurofibromin, diagnostic criteria, clinical findings