title: Gene panel sequencing improves the diagnostic work-up of patients with idiopathic erythrocytosis and identifies new mutations.
abstract: Erythrocytosis is a rare disorder characterized by increased red cell mass and elevated hemoglobin concentration and hematocrit. Several genetic variants have been identified as causes for erythrocytosis in genes belonging to different pathways including oxygen sensing, erythropoiesis and oxygen transport. However, despite clinical investigation and screening for these mutations, the cause of disease cannot be found in a considerable number of patients, who are classified as having idiopathic erythrocytosis. In this study, we developed a targeted next-generation sequencing panel encompassing the exonic regions of 21 genes from relevant pathways (~79 Kb) and sequenced 125 patients with idiopathic erythrocytosis. The panel effectively screened 97% of coding regions of these genes, with an average coverage of 450×. It identified 51 different rare variants, all leading to alterations of protein sequence, with 57 out of 125 cases (45.6%) having at least one of these variants. Ten of these were known erythrocytosis-causing variants, which had been missed following existing diagnostic algorithms. Twenty-two were novel variants in erythrocytosis-associated genes (EGLN1, EPAS1, VHL, BPGM, JAK2, SH2B3) and in novel genes included in the panel (e.g. EPO, EGLN2, HIF3A, OS9), some with a high likelihood of functionality, for which future segregation, functional and replication studies will be useful to provide further evidence for causality. The rest were classified as polymorphisms. Overall, these results demonstrate the benefits of using a gene panel rather than existing methods in which focused genetic screening is performed depending on biochemical measurements: the gene panel improves diagnostic accuracy and provides the opportunity for discovery of novel variants.
authors.affiliation: National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, UK.
authors.forename: Carme
authors.initials: C
authors.lastname: Camps
authors.affiliation: Nuffield Department of Medicine, University of Oxford, UK nayia.petousi@ndm.ox.ac.uk.
authors.forename: Nayia
authors.initials: N
authors.lastname: Petousi
authors.affiliation: Hematology Department, Centro Hospitalar e Universitário de Coimbra, Portugal.
authors.forename: Celeste
authors.initials: C
authors.lastname: Bento
authors.affiliation: Department of Pediatrics and Adolescent Medicine, University Medical Center, Ulm, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Cario
authors.affiliation: National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, UK.
authors.forename: Richard R
authors.initials: RR
authors.lastname: Copley
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University, Belfast, UK.
authors.forename: Mary Frances
authors.initials: MF
authors.lastname: McMullin
authors.forename: Richard
authors.initials: R
authors.lastname: van Wijk
authors.affiliation: Nuffield Department of Medicine, University of Oxford, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ratcliffe
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Robbins
authors.affiliation: National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, UK.
authors.forename: Jenny C
authors.initials: JC
authors.lastname: Taylor
mesh_terms: D014644:Genetic Variation; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods / Q000592:standards; D009154:Mutation; D011086:Polycythemia / Q000175:diagnosis / Q000209:etiology / Q000235:genetics*; D017422:Sequence Analysis, DNA