Of those, 1902 had neurofibromatosis (including 1783 NF1, as described in the Methods), 444 TSC, 63 von Hippel-Lindau disease, and 39 had ataxia-telangiectasia (median [IQR] follow-up among children with neurocutaneous syndromes, 19.9 [10.7-20] years). This evidence concerns the gene NF1 and von Hippel-Lindau disease.