A New Polycythemia Syndrome: Congenital Polycythemia with High Erythropoietin and Propensity for Malignant Hypertension Due to Paraganglioma.

We report three patients, two females and one male, with congenital polycythemia and high erythropoietin. All were extensively investigated in childhood; no known polycythemic conditions were diagnosed nor were any tumors known to be associated with polycythemia uncovered. At the ages of 14, 16, and 32 years the patients developed malignant hypertension secondary to multiple paragangliomas. In addition, one of patients has also developed a malignant pancreatic carcinoid tumor that expressed somatostatin. After the surgical resection of paragangliomas, hypertension subsided, but polycythemia persisted in all three subjects.

Comprehensive screening for germ-line mutations of von Hippel-Lindau (VHL) gene as well as genes known to be causing familial paragangliomas - catalytic succinate dehydrogenase subunits B (SDHB), and catalytic succinate dehydrogenase subunit D (SDHD), has not revealed any mutations. In one of these patients studied so far there was no abnormality of the any of the three hypoxia control associated proline hydroxylase genes expressions found. Unlike the erythroid progenitors of Chuvash Polycythemia, these patients had normal sensitivity of erythroid progenitors to erythropoietin. The search for somatic mutations of VHL, SDHB, and SDHD genes, as well as quantitative analysis of the expressions of hypoxia inducible factor 1 alpha subunit (HIF-1a), vascular endothelial growth factor (VEGF), VHL, SDHB, and SDHD mRNAs by real-time PCR is ongoing.

In summary, we report a new polycythemic syndrome of congenital polycythemia with high erythropoietin and the normal sensitivity of erythroid progenitors to erythropoietin, which is not associated with VHL mutation. This is in contrast to our previous experience with about 200 patients, homozygous for Chuvash Polycythemia mutation or compound heterozygous for Chuvash Polycythemia R200W and other VHL mutations, who have not developed paraganglioma or any VHL syndrome tumors. This new polycythemic syndrome shares some clinical features with both von Hippel Lindau syndrome and with the Chuvash polycythemia. While its molecular defect is yet to be elucidated, it is a distinct clinical and genetic entity.