Based on the knowledge that lack of neurofibromin may lead to a lack of inhibitory control over Ras, resulting in increased cell formation, migration, and differentiation, and based on the existing evidence on volumetric brain abnormalities in NF1, it was hypothesized that subcortical volumes and whole brain gray and white matter volumes would be larger in NF1 compared to healthy controls. This evidence concerns the gene NF1 and neurofibromatosis type 1.