Neurofibromatosis Type 1: A Population-Based Study

To report the incidence, demographics, and clinical manifestations of neurofibromatosis type 1 among a population-based cohort of patients.

The medical records of all patients diagnosed as having neurofibromatosis type 1 while residing in Olmsted County, Minnesota, from January 1, 1980, through December 31, 2009, were retrospectively reviewed.

Fifty patients were diagnosed as having neurofibromatosis type 1 during the 30-year period, yielding an incidence of 1.2 per 100,000 individuals. The mean age at diagnosis was 11.7 years (95% confidence interval [CI]: 0.2 to 47) and 26 (52%) were males. Twenty-eight patients were new mutations, yielding a de novo mutation rate of 56%. During a mean follow-up of 9.8 years (range: 3 weeks to 32 years), café-au-lait macules were diagnosed in 49 individuals (98%), neurofibromas in 26 (52%), and skeletal anomalies in 14 (28%). Three (5.9%) individuals were diagnosed as having glioma of the central nervous system (95% CI: 1.2 to 9.7%) at a mean age of 13 years (range: 5 to 26 years), including 1 patient with optic nerve glioma diagnosed at the age of 26 years. Only 1 (2%) patient was diagnosed as having malignant nerve sheath tumor.

Although the prevalence and de novo mutation rate of neurofibromatosis type 1 in this population-based study were similar to prior reports, the occurrence of optic nerve gliomas was much lower. [J Pediatr Ophthalmol Strabismus. 2019;56(4):243-247.].