地中海贫血和血红蛋白胰岛素血红蛋白病thalassemiaand

THALASSEMIAS AND HEMOGLOBINOPATHIES,CLS 843 ADVANCED CLINICAL HEMATOLOGY Raymond L. Olesinski 2001 University of Kentucky,Thalassemias and Hemoblobinopathies: Module Objectives,At the end of this module you should be able to Explain the pathophysiology that causes thalassemia and hemoglobinopathies Explain how thalassemias are categorized?,Thalassemias and Hemoblobinopathies: Session Objectives,Correlate the results of laboratory testing with specific thalassemias and hemoglobinopathies,Thalassemias and Hemoblobinopathies: Session Objectives,For the 1. Dithionite tube test 2. Hemoglobin electrophoresis 3. Alkali denaturation test for fetal hemoglobin Discuss specifics of specimen collection, handling, storage, and preparation,Thalassemias and Hemoblobinopathies: Session Objectives,Explain the physiologic theory relevant to the test/procedure Explain the principle of the test/procedure Identify the disease manifestation/clinical correlation Differentiate or resolve technical, instrument, or physiologic causes of problems or unexpected test results,Characteristics: Thalassemia,Hereditary disorders that can result in moderate to severe anemia Basic defect is reduced production of selected globin chains,Characteristics: Hemoglobinopathies,Hereditary disorders that can result in moderate to severe anemia Basic defect is production of an abnormal globin chain,Demographics: Thalassemia,Found most frequently in the Mediterranean, Africa, Western and Southeast Asia, India and Burma Distribution parallels that of Plasmodium falciparum,Demographics Hemoglobinopathies,The demographics of hemoglobinopathies are varied Consult Clinical Hematology for more details,Hemoglobinopathy Genetics,Homozygous: Inheritance of two genes from each parent coding for the same type of abnormal hemoglobin, e.g., Hb SS Heterozygous: Inheritance of genes from each parent which code for a deferent type of abnormal hemoglobin each, e.g., Hb SC,Classification & Terminology Alpha Thalassemia,Terminology Silent carrier Minima Minor Intermedia Major,Symbolism Alpha Thalassemia,Greek letter used to designate globin chain, e.g., ,Symbolism Alpha Thalassemia,/ : Indicates division between genes inherited from both parents, e.g., /,Symbolism Alpha Thalassemia,- : Indicates a gene deletion, e.g., -/,Classification & Terminology Alpha Thalassemia,Normal / Silent carrier - / Minor -/- -/ Hb H disease -/- Barts hydrops fetalis -/-,Terminology Other Thalassemia,+: Indicates diminished, but some production of globin chain by gene, e.g., +,Terminology Other Thalassemia,0 :Indicates no production of globin chain by gene, e.g., 0,Terminology Thalassemia,Superscript T denotes nonfunctioning gene, e.g., T,Classification & Terminology Beta Thalassemia,Normal / Minima /SC Minor /0 /+ Intermedia 0/0 0/+ Major 0/0 +/+,Terminology Hemoglobinopathy,Abnormal hemoglobins discovered earlier have been given letter designations, e.g., Hb S,Terminology Hemoglobinopathy,More recently discovered hemoglobins have been named by the city or location of discovery, e.g., Hb C-Harlem,Amino Acid Substitution Hemoglobinopathy,Greek letter designates affected globin chain,Amino Acid Substitution Hemoglobinopathy,Superscript number designates affected amino acid(s), e.g., 6,Amino Acid Substitution Hemoglobinopathy,Letters and numbers in parentheses designate the helical segment and amino acid sequence in that segment affected (sometimes omitted), e.g., 6(A3),Amino Acid Substitution Hemoglobinopathy,Amino acid substitutions are denoted by the three letter abbreviation for the normally occurring amino acid followed by an arrow followed by the three letter abbreviation for the substituted amino acid, e.g., 6(A3)Glu Val,Classification: Hemoglobinopathy,Functional Abnormality Aggregation Polymerization Crystallization Unstable hemoglobins Methemoglobin Oxygen affinity,Special Cases Thalassemia,Hb Lepore: thalassemia Hb Constant Spring chain with 31 additional amino acids -/cs Hereditary persistence of fetal hemoglobin (HPFH),Special Cases: Thalassemia,Hb H 4 tetramer Associated with -/- thalassemia,Special Cases: Thalassemia,Hb Barts & hydrops fetalis Barts is a 4 tetramer Associated with -/- Lethal High concentrations are capable of sickling,Primary Laboratory Investigation Thalassemia,Variable hemogram results proportional to the severity of the thalassemia,Primary Laboratory Investigation Thalassemia,Severe cases present with Microcytosis Hypochromia Poikilocytosis RBC counts higher than expected for the level of anemia,Primary Laboratory Investigation Thalassemia,Findings in severe cases can mimic those seen in other microcytic/hypochromic anemias Results of the reticulocyte count are variable NRBCs may be present (contrast with iron deficiency anemia),Primary Laboratory Investigation Hemoglobinopathy,Variety of hemogram findings depending on Type Severity of the specific disorder Only sickle hemoglobinopathies and Hb C will be described here,Primary Laboratory Investigation Heterozygous & Other Disorders,AS S-Thal Other hemoglobinopathies, e.g., SC Hb C,Morphologic Findings Hb SS vs. Hb SC vs. Hb CC,Morphologic Findings Hb SS vs. Hb SC vs. Hb CC,+,=,Where Do Sickle Cells Come From?,Sheared in microcirculation,Irreversible Sickle Cell,Sickle Cells,Secondary Laboratory Investigation,Hemoglobin electrophoresis Major test for identifying thalassemia and hemoglobinopathy Types Cellulose acetate: Alkaline pH Citrate agar: Acid ph,Secondary Laboratory Investigation,Patterns of mobility (see Fig. 14-4, Clinical Hematology, p. 202) Limitations Sources of error,Secondary Laboratory Investigation Cellulose Acetate Hb Electrophoresis,- A2/C S F A + Normal,Secondary Laboratory Investigation Cellulose Acetate Hb Electrophoresis,- A2/C S F A + Normal Hb SS,Secondary Laboratory Investigation Cellulose Acetate Hb Electrophoresis,- A2/C S F A+ Normal Hb SS Hb AS,Secondary Laboratory Investigation Cellulose Acetate Hb Electrophoresis,- A2/C S F A+ Normal Hb SS Hb AS Hb SC,Secondary Laboratory Investigation Cellulose Acetate Hb Electrophoresis,- A2/C S F A+ Normal Hb SS Hb AS Hb SC Hb CC,Secondary Laboratory Investigation Cellulose Acetate Hb Electrophoresis,- A2/C S F A+ Normal Hb SS Hb AS Hb SC Hb CC HB AD,Secondary Laboratory Investigation,Solubility testing-Dithionite tube test Alkali denaturation test for quantification of fetal hemoglobin Acid elution test for fetal hemoglobin distribution Unstable hemoglobin testing for Heinz bodies,Alkali Denaturation for Hemoglobin F,Recommended assay for hgb F in the range of 2-40% Principle Other hemoglobins are more susceptible than hgb F to denaturation at alkaline pH Denaturation stopped by addition of ammonium sulphate Denatured hemoglobin precipitates,Alkali Denaturation for Hemoglobin F,Remaining hemoglobin (F) can be measured spectrophotometrically Specimen: EDTA anticoagulated whole blood QC: Normal and elevated controls should be used with each batch of specimens,Alkali Denaturation for Hemoglobin F,Hgb F, % Diff. between Duplicates, % 15 2.0,Alkali Denaturation for Hemoglobin F,Sources of error Too short or too long an incubation time filtrate turbidity Outdated reagents Incorrect reagent concentrations Poor quality filter paper,Acid Elution for Fetal Hemoglobin,Indication of distribution of fetal hemoglobin in a population of RBC Homogeneous distribution: hereditary persistence of fetal hemoglobin Heterogeneous distribution: thalassemia,Course and Treatment Thalassemia,Time of presentation Related to degree of severity Usually in first few years of life Untreated severe thalassemia -/-: Prenatal or perinatal death -/- & -/cs: Normal life span with chronic hemolytic anemia,Course and Treatment Thalassemia,Untreated thalassemia Major: Death in first or second decade of life Intermedia: Usually normal life span Minor/Minima: Normal life span,Course and Treatment Sickle Cell Disease,Sickle cell disease Asymptomatic at birth Symptoms appear as percentage of fetal hemoglobin decreases during first year of life Untreated crises increase morbidity and early death,Course and Treatment Sickle Cell Disease,Life span can be significantly increased with early and effective treatment Studies of natural populations reveal that individuals with sickle cell disease are capable of normal life spans,Course and Treatment,In both thalassemia and hemoglobinopathy therapy is usually supportive rather than curative,Course and Treatment,Blood transfusion is used to Control severe anemia Reduce the risk of complications of sickle hemoglobinopathies (cere