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Hemoglobinopathies
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Hemoglobinopathies Disorders of Hemoglobin Dr. Pupak Derakhshandeh
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Disorders of Hemoglobin 5 % of world population: carrier for genes, important disorders of hemoglobin
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Structure and function of hemoglobin Oxygen carrier In vertebrate: red blood cells Four subunits: 2α- and 2 -chains
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Hemoglobin
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Each Subunits Globin: Polypeptide chain Heme : Prosthetic group (Iron-Containing pigment) Heme + Oxygene Oxygene transporting
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Normal adult hemoglobin HbA: 2 α globin chain (141 AA) 2 globin chain (146 AA) α22 α22 α22 α22 Equal length
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Normal adult hemoglobin HbF: 2 α globin chain 2 γ globin chain α2γ2 α2γ2 α2γ2 α2γ2
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Normal adult hemoglobin
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Hemoglobin in the Ontogenesis
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Thalassemia Onset: Childhood Hypo chromic / Microcrystal anemia Low level of MCV / MCH Mean corpuscular volume (MCV) Mean corpuscular hemoglobin (MCH) -Thal: Elevated HbA 2 ( α 2 2 ) HbF ( α 2 γ 2 ) HbF ( α 2 γ 2 ) α -Thal: Normal HbA 2, HbF
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Thalassemia Minor
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Thalassemia minor is an inherited form of hemolytic anemia that is less severe than thalassemia major. This blood smear from an individual with thalassemia shows small (microcytic), pale (hypochromic), variously-shaped red blood cells. These small red blood cells (RBCs) are able to carry less oxygen than normal RBCs.
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Thalassemia Major
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an inherited form of hemolytic anemia red blood cell (hemoglobin) abnormalities the most severe form of anemia the oxygen depletion in the body becomes apparent within the first 6 months of life Thalassemia major
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If untreated, death usually results within a few years Note the small, pale (hypochromic), abnormally-shaped red blood cells associated with thalassemia major The darker cells likely represent normal RBCs from a blood transfusion
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Diesease Autosomal recessive Deficiency: Synthesis of α/ - globin Origin: Mediteranean, African, Iranian, Indian, Southeast Asian Resistant to malaria
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Prevalence of α-Thalassemia 0.01 % in non malarial areas ig. UK, Japan ig. UK, Japan ~ 49 % in Soutwest Pasific Islands
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Defected globin chains
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Prevalence of -Thalassemia ~ 1.5 % in Africans and African Americans ~ 30 % in Sardinia
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Pathogenesis of -Thalassemia In adequate Hb production Reduced MCV/MCH Unbalanced accumulation of globin subunits Ineffective Erythrocyt 200 different mutations In Iran about 60 mutations
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α globin mutations Deletions: 80-85 % of αThalassemia Del: 3.7 kb (most frequent) Del: 4.2 kb α 2 InsI-5bp deletion (α Hph1 α) α 2 InCd T>C (α Nco1 α) α º Variant: --MED --CAL --SEA
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-Thalassemia Trait - –Hemoglobin is with in the reference range. –Reticulocyte count is within the reference range. –Mean corpuscular volume (MCV) is 75-85 fL. –Mean corpuscular hemoglobin (MCH) is 26 pg.
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a-Thalassemia Alpha1 thalassemia minor (--/ ) –Hemoglobin is within the reference range. –Reticulocyte count is within the reference range. –MCV is 65-75 fL. –MCH is 22 pg.
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Hemoglobin H disease Peripheral smear from a patient with hemoglobin H disease showing target cells, microcytosis and hypochromia. Morphological abnormalities are similar to those observed in beta thalassemia. In alpha2 thalassemia (silent trait) only mild microcytosis is observed.
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HbH disease Hemoglobin H disease –Hemoglobin is 7-10 g/dL. –Reticulocyte count is 5-10%. –MCV is 55-65 fL. –MCH is 20 pg. –The peripheral blood smear shows small misshapen red cells, hypochromia, microcytosis, and targeting. –Brilliant cresyl blue stain demonstrates hemoglobin H inclusion bodies.
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HbH disease Functional α globin : 1 α: globin ratio : 0.3 Hb level: 7-9 g/dl Genotype: --/-α HbH Inclusion (Heinz body): Many Moderate anemia Hepatosplenomegaly Galstones, infection, folic acid deficiency
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Hydrops fetalis –Hemoglobin is 4-10 g/dL. –MCV is 110-120 fL. –The peripheral blood smear shows severe hypochromia, and nucleated red blood cells.
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Hydrops fetalis Functional α globin : 0 α: globin ratio : 0.0 Genotype: --/-- HbH Inclusion (Heinz body): Present Severe anemia Heart defect/fatal in utero/ shortly after birth
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Treatment Avoid iron supplementation. It contributes to iron overload Administer folate supplementation to provide adequate amounts of the vitamin for increased utilization resulting from the hemolytic process and high bone marrow turnover rate. Provide prompt attention to infection, especially in children who have had a splenectomy. Administer blood transfusions only if necessary. If chronic transfusion is needed (hemoglobin H disease), iron chelation therapy should be considered to avoid iron overloading.
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Surgical Care Hemoglobin H disease –Perform a splenectomy if transfusion requirements are increasing. –Surgical or orthodontic correction may be necessary to correct skeletal deformities of the skull and maxilla due to erythroid hyperplasia.
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globin mutations 1.Transcriptional mutations ( + ) In promotor regulatory elements -101(silent) -92 (silent) -88 -30
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globin mutations 2. RNA-Processing ( º ) Splice junction IVSI-1 Cd30 IVSI-2 IVSI-3’ end del 25bp IvsI-130 Consensus splice sites ( º/ + ) IVSI-5 IVSI-6 IVSII-844
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globin mutations Cryptic splice sites in Introns ( + ) IVSI-110 IVSII-745 Cryptic splice sites in exons Cd 26 (HbE) Cd 121 (HbD panjab/O Arab)
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-Thalassemia major Onset: 6 months Severe hemolytic anemia Hb level< 7 g/dl Skin: pale Growth retardation don’t eat or sleep well Hepatosplenomegaly Bone marrow expansion: Make more red cells Expantion in face and skull Spleen: destroy of young red cell 80% of untreated patients: † by 5 y. Treatment: Cardiac/Hepatic: † by 30 y. Transfusion +Chelation > 30y.
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Thalassemia major
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Treatment Blood transfusion (3-4 weeks for life) Iron accumulation in body Remove the iron: Desferal: Infused under the skin (8-12 h/6 times a week) Bone marrow transplantation A sib brother or sister HLA matched
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Sickle Cell disorder
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Stuck the red cell in the vessels In children: Spleen, chest, wrists,ankles In adults: hips and shoulders Anemia (Hb 7-8 g/dl) Infections (take antibiotics) Painful crises (6-18 months) Swollen and inflamed (hand/food syndrome)
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What are the Complications? pain episodes increased infections bone damage yellow eyes or jaundice early gallstones lung blockage kidney damage and loss of body water in urine painful erections in men (priapism) blood blockage in the spleen or liver (sequestration) eye damage low red blood cell counts (anemia) delayed growth
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Prenatal diagnosis I. ARMS-PCR (22 common mut.) II. PCR-RFLP (9 inf. RFLPs) III. RDB (60 mut.) IV. Sequencing
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ARMS-PCR 1 2 3 4 5 6 7 8 9 10 11 12 13
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PCR-RFLP 1 2 3 M 4 5 6 7
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The combination of hemoglobinopathies Doesn't cause any health problem: α + Thalassemia / α + Thalassemia HbH disease: α º Thalassemia / α + Thalassemia Hydrops fetalis: α º Thalassemia / α º Thalassemia
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Doesn't cause any health problem α + / º Thalassemia/ Thalassemia α + / º Thalassemia / HbC α + / º Thalassemia / HbD α + / º Thalassemia / HbE α + / º Thalassemia / HbO Arab α + / º Thalassemia / HbS
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Thalassemia / Thalassemia Caused severe health problem!
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Other combinations HbC / Thalassemia (no problem) HbD / Thalassemia (no problem) HbE / Thalassemia (serious anemia) Hbs / Thalassemia (intermediate-severe) HPFH* / Thalassemia (no problem) *Heriditary persistance of fetal hemoglobin
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Doesn't cause any health problem HbC / HbC HbC / D, E, O Arab, HPFH HbD / HbD HbD / C, E, O Arab, HPFH HbE / HbE HbE / C, D, O Arab, HPFH
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Doesn't cause any health problem HbO Arab / HbO Arab HbO Arab/ C, E, D, HPFH HPFH / HPFH HbH / Thalassemia ! Thalassemia major/α +/º Thalassemia! Thalassemia major / HbC, D
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serious anemia HbH / α +/º Thalassemia HbS / Thalassemia HbS / HbC HbS / HbD HbS / HbE HbS / O Arab
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Prenatal Diagnosis (PND)
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Thank for Your Attention Attention
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