Clinical and functional properties of novel VHL mutation (X214L) consistent with Type 2A phenotype and low risk of renal cell carcinoma.

This report describes clinical characteristics in families with a Type 2A phenotype and functional properties of a novel von Hippel Lindau variant (X214L). Pedigrees were analyzed. Analysis of von Hippel Lindau (VHL) coding exons and flanking intronic sequences in DNA from a proband with pheochromocytoma and islet cell tumor was performed. Western blot assays for VHL protein (pVHL), HIFα, and Jun B were conducted using VHL null renal clear carcinoma cell lines that were engineered to produce wild-type or X214L mutant pVHL. Pedigree analysis indicated that the variant tracked with disease and the same or similar VHL point mutations were identified in several Type 2A families. The predicted 14 amino acid extended pVHL variant, when reintroduced into VHL null cells, was stable and retained the ability to downregulate HIFα in a hydroxylationdependent manner. In contrast, the variant was defective with respect to downregulation of JunB. pVHL X214L, like other pVHL variants associated with a low risk of clear cell renal carcinoma, largely preserves the ability to downregulate HIF. In contrast, this variant, like other pVHL variants linked to Type 2A disease, fails to suppress JunB. This underscores that JunB may play a role in the pathogenesis of Type 2A VHL disease.