Neurofibromatosis type 1 is an autosomal dominant neurocutaneous disorder characterized by a mutation of the neurofibromin 1 (NF1) gene, resulting in increased susceptibility for multiple tumors, namely, gastrointestinal stromal tumors (GISTs)-the most common types of mesenchymal neoplasms in the gastrointestinal tract. The gene discussed is NF1; the disease is neurofibromatosis type 1.