Thallasmia
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Thallasmia

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Thallasmia Thallasmia Presentation Transcript

  • "Pleasure in the job puts perfection in thework." -- Aristotle :
  • Hemoglobinopathiesare disorders affecting the structure, function or production of hemoglobin
  • Thalassemia is one of them
  • Thalassemia• Hemoglobin• Haem + Globin• Globin – 4 chains - , , ,■ - 3 Types• HbA (Normal Hemoglobin- 2 2)• HbF ( o• HbA2 (A2• 2 )• Each chain has specific aminoacid combination• When aminoacids altered by deletion or addition, mutation –abnormal hemoglobins are formed.
  • Thalassemia• Hemoglobin critical for normal oxygen delivery totissues• Normal RBC life span – 120 days• Hemoglobin is present in erythrocytes in such highquantities that it can alter red cell shape, deformability andviscosity.
  • Hemoglobin Review• Each complex consists of : – Four polypeptide chains, non-covalently bound – Four heme complexes with iron bound – Four O2 binding sites
  • Globin Chains• Alpha Globin – 141 amino acids – Coded for on Chromosome 16 – Found in normal adult hemoglobin, A1 and A2• Beta Globin – 146 amino acids – Coded for on Chromosome 11, found in Hgb A1• Delta Globin – Found in Hemoglobin A2--small amounts in all adults• Gamma Globin – Found in Fetal Hemoglobin• Zeta Globin – Found in embryonic hemoglobin
  • Hemoglobin Types Hemoglobin Type Globin Chains• Hgb A1—92%--------- α2β2• Hgb A2—2.5%-------- α2δ2• Hgb F — <1%--------- α2γ2• Hgb H ------------------ β4• Bart’s Hgb-------------- γ4• Hgb S-------------------- α2β26 gluval• Hgb C------------------- α2β26 glulys
  • Thalassemia• Thalassemias are genetic disorders in which synthesisof normal polypeptide chain forming adult hemoglobinis suppressed.• Selective deficiency of one or more polypeptidechains have two consequences• 1. R Hb – Anemia & e• 2. Cell Membrane damage leading to prematuredestruction of cells
  • 2 -Thalassemia• Decreased production of chains.• Total 4 genes code for 4 chains• 2 genes on each chromosome 16
  • Types of Thalassemia• 2 Classifications• First Type a. Thalassemia Major (Profound Anemia) b. Thalassemia Intermediate c. Thalassemia Minor d. Thalassemia Minima• Second Type a. Alpha Thalassemia b. Beta Thalassemia
  • > -Thalassemia -Thalassemia• Classification - -Thalassemia 2 trait (One of 4 genes deleted) - -Thalassemia 1 trait (Two of 4 genes deleted) - HbH disease > Three genes deleted > No specific treatment required > Avoid iron therapy > Folic acid if necessary - Hydrops fetalis (Hb Bart’s) > All 4 genes deleted > In utero death of foetus > No treatment available
  • Alpha Thalassemias• Result from gene deletions• One deletion—Silent carrier; no clinical significance• Two deletions—α Thal trait; mild hypochromic microcytic anemia• Three deletions—Hgb H; variable severity, but less severe than Beta Thal Major• Four deletions—Bart’s Hgb; Hydrops Fetalis; In Utero or early neonatal death
  • Alpha Thalassemias• Usually no treatment indicated• 4 deletions incompatible with life• 3 or fewer deletions have only mild anemia
  • Beta Thalassemia• Point mutation in gene for non alpha producing chain inchromosome 11- Two types• Beta Thalassemia Major ( r 0 )• Beta Thalassemia Minor ( r - )
  • Beta Thalassemia Major Also called Cooley’s Anemia • Clinical Features - Severe hypochromic anemia - Erythroblastosis - Grossly b l HbA - Increase in HbF
  • Beta Thalassemia Major• Treatment - Bone Marrow transplantation - Avoid Iron therapy - If iron overload, Desferoximine therapy - Splenectomy
  • Beta Thalassemia Minor• Clinical Features - Mild anemia - Some target cells - Punctate basophilia - resistance of RBC to osmotic lysis
  • β-Thalassemia Major--Treatment• Chronic Transfusion Therapy – Maximizes growth and development – Suppresses the patient’s own ineffective erythropoiesis and excessive dietary iron absorption – PRBC transfusions often monthly to maintain Hgb 10-12• Chelation Therapy – Binds free iron and reduces hemosiderin deposits – 8-hour subcutaneous infusion of deferoxamine, 5 nights/week – Start after 1year of chronic transfusions or ferritin>1000 ng/dl• Splenectomy--indications – Trasfusion requirements increase 50% in 6mo – PRBCs per year >250cc/kg – Severe leukopenia or thrombocytopenia
  • β-Thalassemia MajorComplications and Emergencies• Sepsis—Encapsulated organisms – Strep Pneumo• Cardiomyopathy—presentation in CHF – Use diuretics, digoxin, and deferoxamine• Endocrinopathies—presentation in DKA – Take care during hydration so as not to precipitate CHF from fluid overload
  • How to Prevent ThalassemiaThis disease is inherited. Blood tests andfamily genetic studies will show if you area carrier. A genetic counselor can discussrisks of passing on the disease. They canalso give you information on testing.