High frequency of mosaicism among megabase Nf1 deletions

Background: neurofibromatosis 1 is an autosomal dominant disorder characterized by tumors of the nerves systems and various cognitive deficits. The cause of neurofibromatosis is the defect of a tumor suppressor gene, NF1, 17q. A small group of the patients have facial anomalies associated with mental retardation and large number of tumors. Deletion of the entire NF1 gene has often been found in this patient group. However, most previous studies included only patients with the defined phenotypes and no screening has been carried out in a large number of unselected neurofibromatosis 1 patients. Methods: 611 unsele…