Status of the NF1 tumor suppressor locus in uveal melanoma

Background: A clinical association has been observed between uveal melanoma and neurofibromatosis type 1 (NF1). This study aims to determine whether the NF1 tumor suppressor gene is mutated in uveal melanoma. Methods: Thirty-eight uveal melanomas, as well as normal uveal melanocytes, were examined for NF1 deletions by dual-color fluorescence in situ hybridization, and for expression of the NF1 protein (neurofibromin) by immunohistochemistry and Western blot analysis. Results: Normal uveal melanocytes strongly express neurofibromin. Eighteen (47%) of uveal melanomas demonstrated weak expression of neurofibromin. One large tumor contained a deletion of the NF1 locus and lacked neurofibromin expression. Two other tumors contained additional copies of the NF1 chromosomal region. Conclusion: Mutations of the NF1 gene may occasionally play a role in the pathogenesis of uveal melanoma. Clinical Relevance: A search for biallelic NF1 mutations in uveal melanomas from patients with neurofibromatosis will be of interest to determine whether germline NF1 mutations may predispose to uveal melanoma.