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Echambadi Loganathan S, Kattaru S, Chandrasekhar C, Vengamma B, Sarma PVGK. Novel mutations in EPO-R and oxygen-dependent degradation (ODD) domain of EPAS1 genes-a causative reason for Congenital Erythrocytosis. Eur J Med Genet 2022; 65:104493. [PMID: 35395428 DOI: 10.1016/j.ejmg.2022.104493] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 03/16/2022] [Accepted: 03/26/2022] [Indexed: 12/12/2022]
Abstract
Congenital Erythrocytosis (CE) can be primary or secondary due to the mutations in genes involved in the erythropoietin receptor and oxygen sensing pathway. In this study, 42 patients with 38 unrelated patients and one family (4 patients) who were JAK-2 mutation (both exon 12 and exon 14) negative with high haematocrit values were investigated. The Endogenous Erythroid colony (EEC) assay was performed in all patients, interestingly EEC colonies were high in EPAS1 and EPOR mutated patients compared to non-mutated patients. The sequence analysis of EPAS1 (exon 12), EPO-R (exon-8), VHL (exon-3), and EGLN1 (exon-1) genes in all these patients showed 19% of patients (8/42) had mutations, in exon12 of EPAS1 and exon 8 of EPO-R genes. Two novel missense mutations MW_600850:c.1183G>C, MW_600851:c.1028A>C in EPO-R gene were observed in the study group. One new MW_600849:c.1969C>T nonsense mutation and five MW_619914:c.1715A>G, MW_619915:c.1694G>T, MW_619916:c.1634T>C, MW_600852:c.1771C>G, MW_600848:c.1859G>A novel missense mutations were observed in the EPAS1 gene. Among them, 4 mutations p. (Gln572Arg), p. (Ser565Ile), p. (Ile545Thr), p. (Gln591Glu) in the ODD (Oxygen-dependent degradation) domain of HIF2α, all these variations contributed to the formation of non-functional HIF2α. No mutations were observed in VHL and EGLN1 genes. Using in silico analysis we observed that these mutations contributed to major conformational changes in the HIF2α protein making it non-functional. The mutations in the EPAS1 gene were heterozygous and show autosomal dominant inheritance patterns and we observed in one family. These novel mutations in the EPAS1 (75% (6/8)) and 25% (2/8) EPO-R genes correlating with EEC positivity were observed for the first time in India in CE patients.
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Affiliation(s)
| | - Surekha Kattaru
- Department of Biotechnology, Sri Venkateswara Institute of Medical Sciences and University, Tirupati, Andhra Pradesh, India
| | - Chodimella Chandrasekhar
- Department of Haematology, Sri Venkateswara Institute of Medical Sciences and University, Tirupati, Andhra Pradesh, India
| | - B Vengamma
- Department of Neurology, Sri Venkateswara Institute of Medical Sciences and University, Tirupati, Andhra Pradesh, India
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Anžej Doma S, Drnovšek E, Kristan A, Fink M, Sever M, Podgornik H, Belčič Mikič T, Debeljak N, Preložnik Zupan I. Diagnosis and management of non-clonal erythrocytosis remains challenging: a single centre clinical experience. Ann Hematol 2021; 100:1965-1973. [PMID: 34013406 PMCID: PMC8285333 DOI: 10.1007/s00277-021-04546-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 05/01/2021] [Indexed: 12/31/2022]
Abstract
Erythrocytosis has a diverse background. While polycythaemia vera has well defined criteria, the diagnostic approach and management of other types of erythrocytosis are more challenging. The aim of study was to retrospectively analyse the aetiology and management of non-clonal erythrocytosis patients referred to a haematology outpatient clinic in an 8-year period using a 3-step algorithm. The first step was inclusion of patients with Hb > 185 g/L and/or Hct > 0.52 in men and Hb > 165 g/L and/or Hct > 0.48 in women on two visits ≥ two months apart, thus confirming true erythrocytosis. Secondly, polycythaemia vera was excluded and secondary causes of erythrocytosis (SE) identified. Thirdly, idiopathic erythrocytosis patients (IE) were referred to next-generation sequencing for possible genetic background evaluation. Of the 116 patients, 75 (65%) are men and 41 (35%) women, with non-clonal erythrocytosis 34/116 (29%) had SE, 15/116 (13%) IE and 67/116 (58%) stayed incompletely characterized (ICE). Patients with SE were significantly older and had significantly higher Hb and Hct compared to patients with IE. Most frequently, SE was attributed to obstructive sleep apnoea and smoking. Phlebotomies were performed in 56, 53 and 40% of patients in the SE, IE, and ICE group, respectively. Approx. 70% of patients in each group received aspirin. Thrombotic events were registered in 12, 20 and 15% of SE, IE and ICE patients, respectively. Congenital erythrocytosis type 4 (ECYT4) was diagnosed in one patient. The study demonstrates real-life management of non-clonal erythrocytosis which could be optimized using a 3-step diagnostic algorithm.
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Affiliation(s)
- Saša Anžej Doma
- Department of Haematology, University Medical Centre Ljubljana, Zaloška 7, 1000, Ljubljana, Slovenia.,Faculty of Medicine, University of Ljubljana, Korytkova 2, 1000, Ljubljana, Slovenia
| | - Eva Drnovšek
- Department of Haematology, University Medical Centre Ljubljana, Zaloška 7, 1000, Ljubljana, Slovenia.,Medical Centre for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
| | - Aleša Kristan
- Medical Centre for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
| | - Martina Fink
- Department of Haematology, University Medical Centre Ljubljana, Zaloška 7, 1000, Ljubljana, Slovenia
| | - Matjaž Sever
- Department of Haematology, University Medical Centre Ljubljana, Zaloška 7, 1000, Ljubljana, Slovenia.,Faculty of Medicine, University of Ljubljana, Korytkova 2, 1000, Ljubljana, Slovenia
| | - Helena Podgornik
- Department of Haematology, University Medical Centre Ljubljana, Zaloška 7, 1000, Ljubljana, Slovenia.,Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000, Ljubljana, Slovenia
| | - Tanja Belčič Mikič
- Department of Haematology, University Medical Centre Ljubljana, Zaloška 7, 1000, Ljubljana, Slovenia.,Faculty of Medicine, University of Ljubljana, Korytkova 2, 1000, Ljubljana, Slovenia
| | - Nataša Debeljak
- Medical Centre for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
| | - Irena Preložnik Zupan
- Department of Haematology, University Medical Centre Ljubljana, Zaloška 7, 1000, Ljubljana, Slovenia. .,Faculty of Medicine, University of Ljubljana, Korytkova 2, 1000, Ljubljana, Slovenia.
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