Clinicopathologic and genetic analysis of siblings with NF1 and adult-onset gliomas.

Neurofibromatosis Type 1 (NF1) is a common autosomal dominant neurogenetic disorder characterized by neoplasms involving the nervous system which typically present in children. The development of intracranial tumors in adults with NF1 is uncommon and to our knowledge, siblings with adult onset gliomas have not been previously reported. To perform pathological, clinical and genetic analysis of an unusual family with NF1 and adult onset intracranial gliomas. A 39-year-old woman presented with seizures and aphasia and was diagnosed with an intracerebral tumor. Although there was no family history, she met the accepted clinical criteria for NF1. A biopsy was performed and pathological examination revealed an anaplastic pleomorphic xanthoastrocytoma (PXA). In spite of therapy, she died from complications of tumor recurrence. Her 32-year-old sister developed headaches and was diagnosed with a glioma. Although she did not meet the accepted clinical criteria for NF1, given that she has a sibling with NF1 and a malignancy observed in this disorder, we hypothesize that she also has NF1. Our genetic analysis indicated a shared haplotype in these siblings who developed brain tumors but not in an unaffected sister suggesting that both carry the NF1 disease-producing allele. This haplotype was inherited from their unaffected father indicating a paternal origin of the spontaneous putative mutation in the NF1 gene in this family. NF1 should be a diagnostic consideration when siblings develop intracranial brain tumors even when they develop in adults. Our study supports and extends other reports that broaden the clinical and pathological spectrum of manifestations that can occur in NF1 to include not only adult-onset gliomas but uncommon histological subtypes such as PXA.