Type 1 neurofibromatosis is a rare hereditary monogenic disease with an autosomal dominant inheritance associated with a mutation in the NF1 gene on chromosome 17, which encodes neurofibromin, a protein with tumor-suppressive activity. A large genomic deletion of the NF1 gene is detected in only 5—10% of patients with type 1 neurofibromatosis. A clinical case of type 1 neurofibromatosis associated with a rare extensive deletion of the NF1 gene involving the whole studied gene (exons 1 to 57) in a patient who was observed from early childhood to 17 years of age is presented. The phenotype included early clinical onset with typical skin manifestations, multisystem lesions, sequential progression of diffuse multifocal lesions in the brain and peripheral nervous system, and visual disorders associated with optic glioma.