Increased red blood cell count may result from primary erythrocytosis (polycythemia vera), but it is often due to secondary causes with increased erythropoietin levels. Secondary erythrocytosis may also be congenital due to different gene mutations of hemoglobin, hemoglobin stabilization proteins, EPO receptors, or oxygen sensing pathways. Von Hippel- Lindau gene mutation causes altered tissue oxygen sensation in VHL disease, usually with normal hemoglobin. Germline VHL mutations associate with classical VHL disease and represent genetic susceptibility for pheochromocytoma. VHL polymorphisms are mostly considered an innocent phenomenon. Still, some data indicate that these polymorphisms are not always harmless and can occur with prostate, renal, and colon cancer or even with isolated erythrocytosis. Seventy-eight patients referred to our department with elevated hemoglobin were screened for VHL mutations. There were no classical somatic VHL mutations. However, we found heterozygous (GA) or homozygous (AA) rs779805 VHL c.-195G>A polymorphism accompanied by erythrocytosis. These patients are Jak-2 negative, with normal or elevated EPO levels, sometimes with family accumulations and often phlebotomy needs, and in some cases with malignancies in the family. No other cause of erythrocytosis was found. We use phlebotomy regularly, and for those with cardiovascular risk factors, we recommend aspirin.
Keywords: phlebotomy; rs779805 polymorphism; secondary erythrocytosis; single nucleotide polymorphism; von Hippel-Lindau gene.
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