Congenital Dyserythropoietic anemias: where we are

Transcription

1 Congenital Dyserythropoietic anemias: where we are Achille Iolascon Department of Molecular Medicine and Medical Biotechnology University Federico II of Naples, Italy 6 th EUROPEAN SYMPOSIUM ON RARE ANAEMIAS 1 st Dutch-Belgian meeting for patients and health professionals 21 st - 22 nd November 2015 Amsterdam - The Netherlands

2 Disclosure Nothing to disclose

3 This talk is applicable for: Thalassemia s Sickle cell disease Membrane disorders (e.g. sferocytosis) Enzym defects (e.g. PKD, G6PD) PNH Other forms of hemolytic disease Definite yes no yes no no yes Probable

4 Congenital dyserythropoietic anemia with karyorrhexis and multinuclearity of erythroblasts. Heimpel H, Wendt F. Helv Med Acta Mar;34(2): [Congenital dyserythropoietic anemia]. Heimpel H, Wendt F, Klemm D, Schubothe H, Heilmeyer L. Arch Klin Med. 1968;215(2): [A new variant of the congenital dyserythropoietic anemia]. Heimpel H, Wendt F. Schweiz Med Wochenschr Nov 4;97(44): [Congenital dyserythropoietic anemia in a pair of dizygotic twins]. Wendt F, Heimpel H. Med Klin Feb 3;62(5):172-7.

5 Congenital Dyserythropoietic Anemias (CDAs) CDAs are mendelian diseases affecting the normal differentiation-proliferation pathway of the erythroid lineage. They belong to a subtype of bone marrow failure syndromes characterized by monolineage involvement and morphological abnormalities in erythroid precursor cells Erythroid hyperplasia with specific morphological alterations involving late erythroblasts Mild hemolytic anemia (9-10 g/dl) Reduced reticulocyte count Jaundice Splenomegaly Hemosiderosis Gallstones Transfusion dependence ( 20%) Williams Hematology, Nineth Edition, Chapter 39 by A. Iolascon - McGraw-Hill _ In press

6 Congenital Dyserythropoietic Anemias

7 Percentage Age at diagnosis of CDAs Percentage Age at diagnosis CDA I (n=23) CDA II (n=106) <5 <10 <15 <20 <25 <30 <35 <40 <45 <50 >50 Age (years) Onset age CDA II (n=89) Pre-natal <1 <5 <15 >15 Age (years)

8 Clinical findings of CDAs Anemia Jaundice Splenomegaly Gallstones Iron overload

9 Differential diagnosis HS CDA II Reticulocyte count Splenectomy is the standard treatment Unc. Bilirubin LDH Haptoglobin Hepatosplenomegaly Reticulocyte count Splenectomy slightly increases Hb level Autosomal dominant (75%) RDW Hemosiderosis RDW Autosomal recessive Normal or slightly increased stfr stfr

10 Preliminary study design for DD: tngs approach Pilot study Selection of 15 patients: 6 with known genotype; 6 with unknown genotype; 1 family Panel of 10 causative genes of HS and CDAs ( ) Coding regions, UTRs, regulatory regions, 100 bp flanking splice junctions Inheritance pattern and validation by Sanger sequencing

11 Variants in clinical report of targeted-ngs-based diagnosis for HHA patients Total variants Off-target gene variants Target gene variants Intronic and regulatory gene variants Coding gene variants Variants related to clincal phenotype Variants modifying clinical phenotype SPTA1 α-lely Complete pedigree (12-father; 13-mother; 14-proband; 15-unaf. sister)

12 Polygenic contribute in monogenic disease Hereditary Spherocytosis -SPTA1 mutations - αlely variant Dyserythropoietic phenotype -SEC23B mutation -GATA1 modifier variant

13 Indirect Bilirubin levels and Incidence of gallstone formation in CDAN2 patients divided by their UGT1A genotype UGT1A1 Ind.Bil Gallstones No Gallstones (TA)6/(TA)6 or (TA)6/(TA) % 76% (TA)7/(TA) % 12.5%

14 Iron Overload in CDAs : relevance of this complication

15 Hematological and iron data of CDAII patients (1) Patient Gender Age Haemoglobin (g/dl) Erythrocytes (10 12 /l) Hematocrit (%) MCV (fl) Reticulocytes (10 9 /l) Iron (µmol/l) Transferrin (g/l) Transferrin saturation (%) Ferritin (µg/l) Soluble Tfr (mg/dl) Hepcidin (nm) 1 m f f m f f f f f m m f f f f m m f nd f f m m m f f f f f m f f f m GDF15 (pg/ml)

16 Hematological and iron data of CDAII patients (2) 35 m f f f m m m f f f m f m m f m m Average SD Age Haemoglobin (g/dl) Erythrocytes (1012/l) Hematocrit (%) MCV (fl) Reticulocytes (109/l) Iron (µmol/l) Transferrin (g/l) Transferrin saturation (%) Ferritin (µg/l) Soluble Tfr (mg/dl) Hepcidin (nm) GDF15 (pg/ml)

17 Pathogenesis of Iron Overload in CDAII P< P<0.016 P<0.005 P<0.002

18 Polychromatic erythroblasts are the main source of ERFE in human and mice Mouse Human The onset of multinuclearity in in vitro model of CDA II involves polychromatic and orthochromatic precursors. Hypothesis: the accumulation of highly expressing-fam132b polychromatic erythroblasts in CDA II marrow could account for the pathological over-expression of ERFE Williams Hematology, Nineth Edition, Chapter 39 by A. Iolascon - McGraw-Hill

19 Classification and distinguishing features of CDAs CDA TYPE I Clinical features: anemia with neonatal appearance; jaundice, splenomegaly; rare syndactyly; Common complication: hemochromatosis Bone marrow morphology - MO: megaloblastoid erythroid hyperplasia; nuclear bridges - ME: spongy-appearing nuclei and invagination of the cytoplasm in the nucleus. Inheritance: Autosomal recessive Locus: 15q (Codanin-1)

20 Mutations in CDAN1 gene

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22 CDA type III Västerbotten family American family

23 CDA III genetics By linkage analysis CDA III locus was mapped to an 11 cm interval on chromosome 15 (15q21-q25) Lind et al, Hum Mol Genet 1995 KIF23 localizes in the midbody KIF23 (MLKP1) localization (green) relative to DNA (blue) in Hela cells

24 Congenital dyserythropoietic anemia 2009: CDA-II, all European Countries

25 CDA II History 1967-CDA II description (H.Heimpel and F.Wendt) 1982-Band 3 hypoglycosilation 1990-Identification of enzimatic deficency 1996-Identification of double membranes on GR surface 1998-Activity reduction of banda Description of natural history of CDA II 1997-Localization of CDAN2 locus in 20q11.2 by genomewide search 2009-Identification of the causative gene

26 SEC23B is a component of COPII complex Russo R et al, Am J Hematol 2012

27 Molecular genetics of CDA II In no case homozygosity or compound heterozygosity for two nonsense mutations was found, a situation likely to be lethal. However, few cases with two hypomorphic mutations have been described so far. Iolascon A et al, Curr Opin Hematol 2011

28 Molecular geocode of SEC23B alleles in Europe Dotted red line highlights the geographical areas where a founder effect has been demonstrated or suggested Russo R et al, Am J Hematol, 2014

29 Dissemination of the E109K mutation in the Mediterranean area Russo R et al, Am J Hematol, 2011

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31 General Pathogenesis of CDAs

32 XVIII Congresso Nazionale SIGU Roberta Russo Antonella Gambale Immacolata Andolfo Luigia De Falco Medical Genetics Unit Acknowledgments