Hematology - 10 Hemoglobinopathies and Thalassemia

HEMATOLOGY ADULT HEMOGLOBINS HEMOGLOBINOPATHIES AND THALASSEMIA Hemoglobin A1 (HbA1) Hemoglobin A2 (HbA2) Fetal Hemoglobin (HbF) OUTLINE • Hemoglobinopathies & Thalassemia • Hemoglobin o Adult Hemoglobins • Hemoglobinopathies o Hemoglobin S o Hemoglobin C o Hemoglobin SC o Hemoglobin E o Other Hemoglobinopathies • Thalassemia o Classification of Thalassemia o Alpha-Thalassemia o Beta-Thalassemia HEMOGLOBINOPATHIES • • HEMOGLOBINOPATHIES & THALASSEMIA • • Heme synthesis defect - Porphyria Globin chain and synthesis disorder • HEMOGLOBIN • (β globin chain) • • • • • Hemoglobin o Contain Heme + 4 globin chains o 4 globin chain - 2 pairs of unlike globin chains ▪ 2 alpha + 2 others ▪ Differentiated by the number and sequence of amino acids ▪ One can cause hemoglopinopathy o Hemoglobinopathy - qualitative defect (substitution in globin chain) o Thalassemia - quantitative defect (decreased production of globin chain) Qualitative defect of globin chain of hemoglobin o At least one substitution of amino acid in polypeptide chain Most common genetic diseases o Inheritance of mutated/defective gene that encodes for the globin chain (parental/maternal inheritance) ▪ Results in amino acid substitution o Inheritance can be homozygous or heterozygous ▪ Homozygous - 2 of the globin chain is affected ▪ Heterozygous - 1 of the globin chain is affected Differentiated from: o Solubility o Electrophoretic mobility Major Groups: o Alpha Hemoglobinopathies ▪ Alpha chain is affected ▪ Affect all adult Hgb (HbA1, HbA2, HbF) ▪ Second most common form hem o Beta Hemoglobinopathies ▪ Most common form ▪ Affect HbA1 (most abundant adult Hgb - 90%) o Gamma Hemoglobinopathies ▪ Rarely encountered ▪ Affect HbF o Delta Hemoglobinopathies ▪ Rare occurrence ▪ Affect HbA2 o Nomenclature is based on globin chain affected HEMOGLOBIN S (HbS) • • GLOBIN CHAINS 2 alpha, 2 beta 2 alpha, 2 delta 2 alpha, 2 gamma Most common and severe abnormal hemoglobin Decreased oxygen affinity Structural Formula: α2ß2 6 GLU→VAL Two States: o Sickle Cell Anemia (HbSS) - homozygous o Sickle Cell Trait (HbAS) - heterozygous (+) Reversible Sickle Cells o RBC that sickles under reduced oxygen environment o Reverts to normal when oxygenated Confined among African, African American, Mediterranean, Middle Eastern, Indian o Blacks - most common o Middle eastern/Indian - some occurrence SICKLE CELL ANEMIA (HbSS) • • • • • A homozygous condition resulting to serious chronic hemolytic anemia o Both chains are affected Confined among black population HbA1 – Absent o Due to alteration of both alpha globin chains Hemoglobin Present: o HbS (80%) o HbF (20%) - compensatory Hgb (to compensate for the decreased oxygen affinity) o HbA2 (variable values) Peripheral Smear: o Normocytic, normochromic o Moderate to marked polychromasia o Normoblasts in PBS o Poikilocytes: sickle cells, target cells ▪ Hallmarks of sickle cell anemia o Inclusions: Howell-Jolly bodies, o Pappenheimer bodies, basophilic stipplings • • Sodium Metabisulfite Test o Principle: Sodium metabisulfite is a reducing agent that will deoxygenate hemoglobin causing polymerization of RBC forming sickle cells o Results: ▪ Normal RBC: Biconcave RBCs ▪ HbS: Sickle cells o Alkaline Hemoglobin Electrophoresis & Acid Hemoglobin Electrophoresis o Acid Hgb Electrophoresis - complementary test for Alkaline Hgb Electrophoresis for confirmation Alkaline • • Laboratory Findings: o RBC: Normocytic, normochromic o Reticulocytosis: 10-25% o WBC, Platelets: increased o OFT: Decreased ▪ Due to sickle cells & target cells (increases surface area to volume ration) o Hgb Solubility Test: Positive o Sodium Metabisulfite Test: Positive o Hemoglobin Electrophoresis: ▪ Cellulose acetate (pH 8.4-8.6): migrates with HbD and HbG ▪ Citrate agar (pH 6.0-6.2): migrates on the anode Hemoglobin Solubility Test o aka Dithionite Tube Test o Principle: ▪ Saponin hemolyzes RBCs (normal or sickle) liberating Hgb ▪ Sodium dithionite (hydrosulfite) converts Fe2+ to Fe3+ resulting to deoxygenation of hemoglobin • Ferric state - methemoglobin (can’t bind O2) o Cause deoxygenation of Hgb • Has the capacity to precipitate • Precipitate cause turbidity o Solubility: ▪ Normal Hemoglobin: Soluble ▪ HbS: Insoluble (turbidity) Acid SICKLE CELL TRAIT (HbAS) • • • • • • • a heterozygous beta-globin chain defect. o Only one globin chain is affected Most common heterozygous trait (US) Often asymptomatic and anemia occurs during extreme hypoxic condition o Due to abundance in HbA1 Resistant to P. falciparum Hemoglobin Present: o HbA1 (60%) o HbS (40%) o HbA2, HbF (normal amount) Laboratory Findings: o RBC: Normocytic, Normochromic o Hemoglobin Solubility: Positive o Sodium Metabisulfite: Positive o Hemoglobin Electrophoresis: HbS & HbA are present Peripheral Smear: o Normocytic, normochromic o Few target cells OTHER SICKLE CELL DISEASES • • • • • • • • Hemoglobinopathies with sickle cells HbSS (sickle cell anemia) HbSC HbSC-Punjab (Los Angeles) HbSO-Arab S-Beta-thalassemia S-hereditary persistence of fetal hemoglobin HbSE HEMOGLOBIN C (HbC) • • • • 2nd most common abnormal hemoglobin Two states: o HbCC – Hemoglobin C disease (homozygous) o HbAC – Hemoglobin C trait (heterozygous) Almost exclusive among African American population Structural Formula: α2ß2 6GLU→LYS HEMOGLOBIN SC (HbSC) • • • HEMOGLOBIN C DISEASE (HbCC) • • • • • Represented with moderate hemolytic anemia with splenomegaly, jaundice and abdominal discomfort Homozygous with two globin chains are affected Hemoglobin Present: o HbC (90%) o HbF (7%) o HbA2 (2%) Laboratory Findings: o RBC: normocytic, normochromic (some microcytic, hypochromic) o Biphasic OFT o Hemoglobin Electrophoresis: ▪ Alkaline: migrates with HbA2, HbE,HbO ▪ Acid: migrates towards the anode • HbCC is most anodal o Peripheral Smear: o Normocytic, normochromic o Mild microcytic, hypochromic (some cases) o Target cells (40-90%) o Slight reticulocytosis: 2-3% (polychromasia) o nRBC o HbC crystal (hexagonal, elongated; bar of gold appearance) • • • • A double heterozygous beta-hemoglobinopathy o Inheritance of heterozygous trait globin chain o Both globin chain in a pair have different defect α2ß6GLU→VALß6GLU→LYS Hemoglobin Present: o HbS (50%) o HbC (50%) o HbF (~7%) Milder form of sickle cell anemia (less severe) o More severe than HbCC Seen in: African, Mediterranean, Middle Eastern Laboratory Findings: o RBC: normocytic, normochromic o Hemoglobin (11-13 g/dL) - light anemia o Reticulocyte (3-5%) o Hemoglobin Solubility: Positive Peripheral Smear: o Few sickle cells, target cells o HbSC crystal – Washington monument appearance ▪ Protruding from RBC membrane HEMOGLOBIN E (HbE) • • • • • • • 3rd most common abnormal hemoglobin Common among southeast Asian, African, and African American. Most common hemoglobinopathy in the Philippines Structural Formula: α2ß2 26GLU→LYS With microcytes and target cells HbEE – mild anemia with microcytes and target cells o 90% HbE HbAE – No anemia o 25-30% HbE OTHER HEMOGLOBINOPATHIES • • HEMOGLOBIN C TRAIT (HbAC) • • • Heterozygous HbC (one globin chain affected) Asymptomatic and represent no anemia Hemoglobin Present: o HbA (60%) o HbC (40%) o HbA2, HbF (normal amounts) • • • • Hemoglobin D (HbD) α2ß226GLU→GLN o Same electrophoretic mobility as HbS but no sickle cells o Differentiation is based on presence of sickle cell Hemoglobin O-arab α2ß2 121GLU→LYS o Mild splenomegaly Hemoglobin G (HbG) α2ß268ASP→LYS o Same electrophoretic mobility as HbS Hemoglobin H (HbH) ß4 o Abnormally unstable Hgb which tends to precipitate in RBC o Exhibits pitted golf ball/raspberry appearance of RBC o Visualized using supravital stain Hemoglobin Bart (Hb-Bart) γ4 o Unstable Hgb which tends to precipitate in RBC Hemoglobin Sydney α2ß211VAL→ALA • • Methemoglobinemias & • Cyanosis o Hb M Saskatoon o Hb M Milwaukee 1 o Hb M Milwaukee 2 o Hb M Boston o Hb M Iwate o Hb M Hyde Park o Hb FM Osaka o Hb FM Fort Ripley Low O2 Affinity • o Hb Agenogi o Hb beth Israel o Hb Yoshizuka o Hb Providence o Hb Titusville o Hb Kansas o May have mild anemia/cyanosis High O2 Affinity o Hb Hiroshima o Hb ranier o Hb Bethesda o Hb Kempsey o Hb Yakima o Hb Malmo o Hb J Cape Town o Hb Chesapeake o Hb Ypsilanti Mild hemolysis w/ intermittent exacerbations o Hb L-Ferrara o Hb Hasharon o Hb Leiden o Hb Freiburg o Hb Seattle o Hb Louisville o Hb Zurich o Hb Gun Hill • HbH disease (Alpha Thalassemia Intermedia) o Three gene deletion (--/-α) o Hemoglobin present: ▪ Hemoglobin H (HbH) – 30% ▪ HbA1 (70%) o Moderate microcytic, hypochromic anemia o Heinz bodies • Hb Bart Hydrops Fetalis Syndrome o Alpha Thalassemia Major o Four gene deletion (--/--) o Hemoglobin present: ▪ Hemoglobin Bart (Hb-Bart) – 80% • Cannot carry oxygen • Lowers oxygen affinity o May cause still birth/hydrops fetalis (fetal death) ▪ Can be prevented by intrauterine transfusion (blood transfusion in fetus) • Increases survival rate but patient will be transfusion-dependent THALASSEMIA • • • Thalassic – “great sea” o Due to high incidence among Mediterranean descent Quantitative defect of globin synthesis o Reduction or total absence of one or more globin chain Laboratory findings: o RBC: microcytic, hypochromic ▪ Almost normal Iron Studies o Polychromasia/Reticulocytosis o nRBCs o Basophilic stipplings o Target cells CLASSIFICATION OF THALASSEMIA • • BETA-THALASSEMIA • • Thalassemia Major – absence of 4 globin chains o Inability to produce sufficient amount of Hgb o Transfusion-dependent patients Thalassemia Minor – decreased rate of alpha/beta globin chain production TYPES OF THALASSEMIA • • Alpha thalassemia o Alpha Thalassemia Major o Alpha Thalassemia Intermedia o Alpha Thalassemia Minor o Silent Carrier State Beta thalassemia o Beta Thalassemia Major o Beta Thalassemia Minor o Beta Thalassemia Intermidia o Silent Carrier State ALPHA-THALASSEMIA • • • Alpha globin has 4 genes Silent Carrier State o Single gene deletion (-α/αα) o No hematologic symptoms/abnormal condition Alpha Thalassemia Minor/Trait o Two gene deletion (--/αα or -α/-α) o Mild microcytic, hypochromic anemia o RBC: increased o Target cells • Silent Carrier (ßsilent/ß) o No hematologic abnormalities Beta-Thalassemia Minor/Trait o aka Cooley’s trait, Rietti-Greppi-Micheli disease o Heterozygous trait o Mild asymptomatic anemia (microcytic, hypochromic) o Laboratory Findings: ▪ Hgb: 11-15 g/dL (men); 10-13 g/dL (women) ▪ RBC, Retics: Normal to slightly elevated ▪ MCV: <75 fL ▪ Poikilocytes (target cells, elliptocytes) ▪ Basophilic stipplings Beta Thalassemia Major o aka Cooley’s anemia, Mediterranean Anemia, Target Cell Anemia o Severe anemia (transfusion-dependent) ▪ Significantly decreased production of β-globin chain ▪ Significantly decreased level of HbA1 (most abundant and most efficient in O2 transport) o Hemoglobin Present: HbF (90%) ▪ HbF - compensatory Hgb o Laboratory Findings: ▪ RBC: microcytic, hypochromic ▪ Poikilocytes (target cells, teardrop cells, elliptocytes) ▪ Inclusion (basophilic stipplings, Howell-jolly bodies, Pappenheimer bodies, Heinz bodies) ▪ Many nRBCs ▪ Increased serum Iron and Bilirubin • Due to sensitivity of RBC to lysis