Clinical Hematology II - HML2143 - PDF

Clinical Hematology II HML2143 1 1 LO1: Describe the hemoglobinopathies with particular regard to their prevalence and importance in the UAE. Week 2: Describe the cause, pathophysiology and clinical effects of alpha and beta thalassemia, together with the curren...

Clinical Hematology II HML2143 1 1 LO1: Describe the hemoglobinopathies with particular regard to their prevalence and importance in the UAE. Week 2: Describe the cause, pathophysiology and clinical effects of alpha and beta thalassemia, together with the currently available treatment options 2 Thalassemia Normal Hemoglobin  Normal Hemoglobin Types of hemoglobin : In fetus: Hemoglobin F (α2γ2)(alpha 2, Gamma 2) In adults: Hemoglobin A (α2β2)- (Alpha 2, Beta 2), ( 96 -98 % ) Hemoglobin A2 (α2δ2) – (Alpha 2, Delta 2), ( 1.5 – 3.0 %) Hemoglobin F (α2γ2) - (alpha 2, Gamma 2), ( 0.5-1.0 % )  Hereditary Hb Abnormalities Also called Hemoglobinopathies, Hb disorders. Most common genetic defect worldwide (tropical, subtropical areas) These genes are most common in areas of the world where malaria was prevalent. UAE has high prevalence of the most common & serious conditions of Hb Pathies “SCD & Thala”  Why Are Hb-Pathies Common? 1. Most carriers of Hb-pathies are asymptomatic. 2. Symptoms are only noted when the person is homozygous for the abnormal gene Note : Defective genes provide carriers with some protection against the worst effects of malaria  Classification Of Hb-pathies: Classified into two types: 1. Quantitative: synthesis of correct Hb structure (α2β2) but low quantity e.g., (Thalassemia) a) Low synthesis of α-chain→ α –thalassemia (Far East) b) Low synthesis of β-chain→ β-thalassemia (Mediterranean) 2. Qualitative: synthesis of wrong Hb structure (globin chain) but correct quantity e.g., (Sickle Cell Anemia) a. Hb variants: crystalline unstable Hb: Hb S, Hb C, Hb D, Hb E→ hemolysis b. All due to substitution in β-chain genes→ chronic intravascular hemolysis.  Thalassemia Definition: Group of disorders characterized by reduction or absence of the production of the globin chains (α or β) Resulting in a variable degrees of anemia. Thalassemia is hereditary conditions (autosomal recessive)  Pathophysiology DNA mutation of one of the globin genes (α or β) → Reduction in the production (low or absence) of the globin chains→ Insufficient pairing between two globin chains (α: β ratio differs) Precipitation of the other normal globin chains within the RBCs→ Hemolytic anemia (HA) (RBCs with reduced life span)  Microcytic Hypochromic Anemia  Thalassemia Two most common types of thalassemia: a) α –thalassemia Low synthesis of α-chain - Common in Africa, the Middle East & SE Asia b) β -thalassemia Low synthesis of β-chain - Common in the Middle East, Mediterranean & the Far East.  Alpha Thalassemia Caused due to α-globin gene deletion So α: β ratio:↓, and β-chain precipitated in the RBCs Pathophysiology: Normally, there are 4 copies of a-globin genes. There are two a-globin genes on each chromosome 16. The clinical severity of a-thalassemia depends on the number of genes that has been deleted.  Alpha Thalassemia The clinical severity can be classified according to the number of α-globin gene deletion: A) One α-gene deletion→ Trait (Silent carrier) (genotype aa/a-) B) Tow α-gene deletions→ Trait (Minor) (genotype aa/-- heterozygous OR, a-/a- homozygous) C) Three α-gene deletions→ Hb H disease (genotype a-/--) D) Four α-gene deletions→ Hydrops fetalis (genotype --/--)  Alpha Thalassemia α-thalassemia trait A) (1 – 2) α-gene deletions→ α-thalassemia trait (minor): Asymptomatic carrier, or mild Diagnosis: CBC: Hb: Normal or slightly ↓ MCV, MCH: Low (slightly) RBCs count: Normal or slightly ↑ Blood Film: May show microcytic hypochromic RBCs Iron profile tests: Normal Hb electrophoresis: Normal  Normal Blood Film Microcytic hypochromic RBCs Hb electrophoresis  Alpha Thalassemia B) 3 α-gene deletions→ Hb H disease (α -Thalassemia major):  Characterized by Hb H mainly (β4)  Moderate to severe microcytic hypochromic anemia (Hb=6-10 g/dl)  Poikilocyosis: Target cells, schistocytes, basophilic stippling, NRBCs, polychromasia in blood film.  Splenomegaly “Golf ball” cells  “Golf ball” cells in brilliant cresyl blue stain. → due to β- chain aggregates Hb H: fast moving band on Hb electrophoresis Hb electrophoresis: Hb H (high) & Hb A (low) 1. Hb Bart’s (γ4): 25% at birth 2. Hb H: 5 to 30% (easily shown in adults)  Poikilocyosis, target cells “Golf ball” cells Alpha Thalassemia Hb Electrophoresis Hb H: 5-30% Hb A: low Some Hb barts (γ4) Confirmation: by increased numbers of Hb H cells after incubation with new methylene blue.  Reticulocyte Remember! Retics can be stained with supravital stain such as brilliant cresyl blue or new methylene blue, by which remnant RNA is stained blue and appears as filaments or granules  Diagnosis Of Hb H disease CBC: low Hb, MCV, MCH Blood film: Romanowesky stain: - Microcytic hypochromic - Poikilocytosis: target cells, schistocyte, polychromasia, NRBCs Brilliant Cresyl Blue stain: Note: In Thalassemia: Serum Fe: Normal or raised -Golf ball cells & reticulocytosis TIBC: Normal or low Hb electrophoresis: Hb H Serum ferritin: Normal or raised HPLC: shows Hb H 2-40 %, Note: CBC parameter that is most helpful to differentiate IDA from Thalassemia is RDW “high in IDA & normal in Thalassemia Hb A2 levels reduced.  Alpha Thalassemia c) 4 α-gene deletions→ Hydrops fetalis: Characterized by Hb barts (γ4) Death in utero or at birth “stillbirth” Hb Bart’s 70 – 80% with some Hb H & Hb Portland Hydrops fetalis No Hb F, HbA2 or Hb A can be formed  Alpha Thalassemia Poikilocytosis, Anisocytosis Hydrops Fetalis Beta Thalassemia Cooley anemia  Beta Thalassemia Caused by single point mutation in β-globin gene. Pathogenesis Normally there is one copy of b-globin gene per chromosome 11. Point mutation leads to reduce (trait) or absence (major) of the synthesis of β-globin chains. So, excess α-chains is precipitated in erythroblasts → ineffective erythropoiesis & in mature RBCs→ hemolysis. Production of γ-chain increases, it binds with excess α-chains & improves the condition.  β-Thalassemia Two types of beta thalassemia: 1) Small amount of β-chain synthesis (b+) → β-thalassemia trait (minor) 2) No β-chain synthesis (b0) → β- thalassemia major  β-Thalassemia minor A) β-thalassemia trait (minor): One gene is affected Small amounts of β-chain synthesis Common, asymptomatic state Like α-thalassemia trait, but more severe: CBC:  RBCs count: normal or ↑  Hb: slightly↓(10-12)g/dl→ mild anemia  MCV, MCH low → microcytic, hypochromic red cells Blood film: Some target cells & possible basophilic stippling. Hb electrophoresis: Hb F↑ (70-80%), HbA2↑ > 3.5%  (3.8 – 8)%, Hb A (10-20%) HPLC: confirms the diagnosis. Iron studies: normal to exclude IDA as a main cause of microcytic hypochromic anemia  β-Thalassemia Major B) β-thalassemia major: Two genes are affected Complete absence of B chain, So NO Hb A, but only Hb F↑ & Hb A2↑. 2 parents with β-thalassemia trait, 25% chance of child with no β- chain synthesis  Clinical Features β-Thalassemia Major 1) Severe anemia (appears at 3-6 months after birth), failure to thrive, pallor, mild jaundice 2) Hepatomegaly, splenomegaly (excessive RBCs destruction, extramedullay hematopoiesis & iron overload (later)) 3) Expansion of bones (BM hyperplasia)→ leading to osteoporosis & skeletal deformities 4) Iron overload→ due to repeated blood transfusion→ if not treated with chelation therapy, it may cause: a) Heart failure b) Liver failure c) Endocrine damage → growth retardation, delay puberty & DM d) Skin pigmentation (grey color) 5) Infections→ Viral (HBV, HCV & HIV) & bacterial (hemophilus, meningococci) frontal bossing of skull Hair-on-end" appearance  Lab Diagnosis Of β-Thalassemia Major CBC: Hb ↓(2.5-6) g/dl, MCV↓, MCH ↓, RDW: normal/ high Blood film: microcytic, hypochromic RBCs Marked anisocytosis & poikilocytosis (Nucleated RBCs, polychromasia, target cells, basophilic stippling, schistocytes) Retics count: ↑ Bone marrow: Erythroid hyperplasia Hb electrophoresis: ↑Hb F (>95%), Hb A2 variable, Hb A: absent HPLC: as results of electrophoresis.  Lab Diagnosis Of β-Thalassemia Major Nucleated RBC’s Target cell Basophilic stippling: small blue RNA granules evenly distributed in RBC Beta thalassaemia major  Lab Diagnosis Of β-Thalassemia Major Chemistry lab: Bilirubin: Increased Urine urobilinogen: Increased Fecal stercobilinogen: Increased LDH: Increased Ferritin, iron: Normal Transferrin receptor: Normal  Treatment Of β-Thalassemia Major 1) Current treatments just sustain the patients; they don’t cure them Regular blood transfusion (2 – 3 units every 4 - 6 weeks) red cell changes become DIMORPHIC (RDW high). Iron chelation therapy→ to remove excess iron Splenectomy→ attempts to lengthen the red cell lifespan & because of the size of the spleen Folic acid therapy 2) BM transplantation (is a cure in small percentage of patients) 3) Eventual treatment in the future will be gene therapy  β -Thalassaemia Intermedia It refers to a clinical phenotype. Patient’s vary in severity from transfusion dependent, to a slightly more severe than β thalassemia minor state. The patient is symptomatic from anemia, Hb: 70 – 80 g/L Moderate to severe microcytic anemia. More severe red cell changes than β thalassaemia trait. Polychromasia & circulating NRBC’s maybe present. Often splenomegaly & sometimes bone deformities.  GENETIC ABNORMALITY CLINICAL SYNDROME a THALASSAEMIAS Haemoglobin Bart’s 4 gene deletion (--/--) hydrops fetalis lethal in utero 3 gene deletion (-a/--) HbH disease haemolytic anaemia 2 gene deletion (aa/--) ao thalassaemia trait microcytic, +/-hypochromic (a-/a-) a+ thalassaemia trait blood picture but usually no anaemia (homozygous) 1 gene deletion (aa/a-) a+ thalassaemia trait Normal Hb, ↓ MCV ß THALASSAEMIAS homozygous thalassemia major severe anaemia, requires transfusions heterozygous thalassaemia minor (trait) microcytic, hypochromic blood picture, anaemia mild or absent thalassaemia intermediate thalassaemia major with less Microcytic, hypochromic anaemia (Hb 70-100g/L); severe clinical picture hepatosplenomegaly, bone deformities, iron overload Hb Lepore ? MCV, MCH low Hb A 80-90% Hb Lepore 10-15%  References McKenzie, Shirlyn/ Landis-Piwowar; Kristin/ Williams, Lynne (2019). Clinical Laboratory Hematology. 4th Ed. Pearson Education. ISBN 9780134709239 Kaushansky/ et al, (2016) Williams Hematology, 9th Ed. McGraw-Hill. ISBN 9780071833011 Lewis, S., Bain, B., Bates, I. (2012) Dacie and Lewis, Practical Haematology, 11th Ed., Churchill Livingstone Elsevier. ISBN: 978-0-7020-3407-7 Hoffbrand, A., Moss, P. (2011) Essential Haematology, 6th Ed. Wiley Blackwell. ISBN: 978-1-4051- 9890-5 Moss, Paul, Pettit, Hoffbrand. Essential Haematology, 5th Ed. Blackwell Science. 2006. ISBN: 9781405136495 Moore, Gary/ Knight, Gavin (2013) Essential Haematology, Oxford University Press ISBN: 9780191666711 800 MyHCT (800 69428) [email protected] www.hct.ac.ae Happiness Center PO Box 25026 Abu Dhabi, UAE HCT_UAE hctuae 39