Neuroibromatosis type I

Introduction The neurofibromatoses are composed of several related tumor predisposition syndromes, and include neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and segmental forms of NF1 and NF2. NF2 affects ~1:38 000 individuals worldwide. Individuals with NF2 harbor Schwann-cell tumors called schwannomas that affect cranial and peripheral nerves, as well as meningiomas and ependymomas. NF1, also known as Von Recklinghausen disease, is one of the most common neurogenetic disorders, affecting 1 in ~2500 people worldwide (1,2). It is an autosomal dominant cancer syndrome with complete penetrance, but variable phenotypic expression. In this regard, individuals within the same family may exhibit different clinical features and associated medical problems. Although NF1 is frequently inherited from a parent with NF1, 30–50% of affected individuals lack a family history of NF1. Non-tumor features of the syndrome include axillary and groin (skinfold) freckling, hyperpigmented macules (café-au-lait spots), bony abnormalities (skeletal dysplasias, dystrophic scoliosis, and tibial pseudarthrosis), and hamartomas of the iris (Lisch nodules), as well as cognitive impairment (3–5).