The association of CNS tumors and neurofibromatosis was studied in a population-based-case control group of 338 patients, less than 15 years of age, diagnosed with a primary tumor of the central nervous system in a ten year period in 53 New York State counties and reported from the Cancer Etiology Unit, Division of Epidemiology, New York State Department of Health, Corning Tower, Albany, NY. The study included 676 controls and information on neurofibromatosis and congenital anomalies. The study confirmed the strong association of neurofibromatosis with the risk of CNS tumors. Thirteen cases and no controls had neurofibromatosis. The types of CNS tumor were optic glioma in 9 patients, astrocytoma in 2, brain stem glioma in 1, and ependymoma in 1. Two fathers and three mothers of these cases had neurofibromatosis and five cases had siblings with neurofibromatosis. Seizures occurred in 37 (12% of 301) cases and in 18 (2.7% of 658) controls. The relative risk of seizures was 4.49 among patients with CNS tumors. There was no difference between cases and controls in the occurrence of congenital anomalies. 
COMMENT. Neurofibromatosis carries an increased risk of CNS tumors including optic gliomas, other astrocytomas, acoustic neurinomas and meningiomas, also neuroblastoma, leukemia and other cancers. The coincidence of optic glioma and neurofibromatosis is especially frequent in children under 10 years of age and in this study the majority of the CNS tumor cases with neurofibromatosis were optic gliomas. Neurofibromatosis is due to an autosomal dominant genetic mutation with 100% penetrance. An important role for genetics in the etiology of some CNS tumors in children is supported by the strong association of neurofibromatosis with the occurrence of CNS tumors and the excess of neurofibromatosis in parents of CNS tumor cases. Children with neurofibromatosis should be examined at regular intervals for possible optic glioma and those with optic glioma should be evaluated for manifestations of neurofibromatosis.