Familial and Congenital Polycythemias: A Diagnostic ApproachVan Maerken, Tom MD*; Hunninck, Kathleen MD*; Callewaert, Luc MD†; Benoit, Yves MD, PhD*; Laureys, Geneviève MD, PhD*; Verlooy, Joris MD*Journal of Pediatric Hematology/Oncology: July 2004 - Volume 26 - Issue 7 - p 407-416 Original Article Abstract Author InformationAuthors The rare absolute polycythemias with an innate and hereditary character can be grouped together under the heading “familial and congenital polycythemias” (FCPs). Primary forms, due to an intrinsic defect in the erythroid progenitor cells, and secondary forms, resulting from extrinsic factors such as an elevated erythropoietin level, have both been reported. Despite the widely divergent characteristics of the different FCPs, the range of possible diagnoses is much more restricted and the distribution of disorders markedly different compared with polycythemias in general. Therefore, in FCP, one can argue against following the algorithm of the Polycythemia Vera Study Group for the evaluation of an elevated hematocrit level, following instead a more specific algorithm. In this article the authors describe a child with primary FCP, review the different FCPs, and propose an adapted work-up scheme. From the *Department of Pediatric Hematology-Oncology, University Hospital Ghent, Belgium; and the †Department of Pediatrics, Algemeen Ziekenuis Maria Middelares, Sint Niklaas , Belgium. Received for publication December 17, 2003; accepted April 19, 2004. Reprints: Dr. Joris Verlooy, Department of Pediatric Hematology-Oncology, University Hospital Ghent, De Pintelaan 185, B-9000 Ghent, Belgium (e-mail: joris.verlooy@Ugent.be). © 2004 Lippincott Williams & Wilkins, Inc.