Paraneoplastic erythrocytosis associated with an inactivating point mutation of the von Hippel-Lindau gene in a renal cell carcinoma

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Abstract
The von Hippel-Lindau (VHL) tumor suppressor gene targets hypoxia-inducible transcription factors (HIFs) for proteasomal degradation. Erythrocytosis due to inappropriate production of erythropoietin (EPO), one of the HIF target genes, is a classic albeit rare finding in patients with renal cancer. We report the clinical to molecular analysis in a patient in whom a thrombotic myocardial infarction was the first manifestation of a clear cell renal carcinoma associated with an elevated serum EPO level (109 U/L) and erythrocytosis (hemoglobin 200 g/L [20 g/dL]). The tumor strongly expressed EPO messenger RNA and the 2 regulatory subunits HIF-1α and HIF-2α. Sequence analysis of tumor tissue identified a point mutation of the VHL gene (nucleotide 701 T>C) with a predicted amino acid exchange (Leu163Pro). This structural change, although located at distance to the HIF-binding region, was found to inhibit binding of HIF-1α to VHL, thus leading to accumulation of HIF, which drives EPO production.