Hemoglobinopathies

Hemoglobinopathies Disorders of Hemoglobin Dr. Pupak Derakhshandeh

Disorders of Hemoglobin 5 % of world population: carrier for genes, important disorders of hemoglobin

Structure and function of hemoglobin  Oxygen carrier  In vertebrate: red blood cells  Four subunits:  2α- and 2  -chains

Hemoglobin

Each Subunits  Globin: Polypeptide chain  Heme : Prosthetic group (Iron-Containing pigment) Heme + Oxygene Oxygene transporting

Normal adult hemoglobin HbA:  2 α globin chain (141 AA)  2  globin chain (146 AA)  α22 α22 α22 α22  Equal length

Normal adult hemoglobin HbF:  2 α globin chain  2 γ globin chain  α2γ2 α2γ2 α2γ2 α2γ2

Normal adult hemoglobin

Hemoglobin in the Ontogenesis

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

Thalassemia Minor

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.

Thalassemia Major

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

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

Diesease  Autosomal recessive  Deficiency: Synthesis of α/  - globin  Origin: Mediteranean, African, Iranian, Indian, Southeast Asian  Resistant to malaria

Prevalence of α-Thalassemia  0.01 % in non malarial areas ig. UK, Japan ig. UK, Japan  ~ 49 % in Soutwest Pasific Islands

Defected globin chains

Prevalence of  -Thalassemia  ~ 1.5 % in Africans and African Americans  ~ 30 % in Sardinia

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

α globin mutations  Deletions: % 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

 -Thalassemia Trait -  –Hemoglobin is with in the reference range. –Reticulocyte count is within the reference range. –Mean corpuscular volume (MCV) is fL. –Mean corpuscular hemoglobin (MCH) is 26 pg.

a-Thalassemia Alpha1 thalassemia minor (--/  ) –Hemoglobin is within the reference range. –Reticulocyte count is within the reference range. –MCV is fL. –MCH is 22 pg.

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.

HbH disease Hemoglobin H disease –Hemoglobin is 7-10 g/dL. –Reticulocyte count is 5-10%. –MCV is 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.

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

Hydrops fetalis –Hemoglobin is 4-10 g/dL. –MCV is fL. –The peripheral blood smear shows severe hypochromia, and nucleated red blood cells.

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

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.

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.

 globin mutations 1.Transcriptional mutations (  + )  In promotor regulatory elements  -101(silent)  -92 (silent)  -88  -30

 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

 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)

 -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.

 Thalassemia major

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

Sickle Cell disorder

 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)

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

Prenatal diagnosis  I. ARMS-PCR (22 common mut.)  II. PCR-RFLP (9 inf. RFLPs)  III. RDB (60 mut.)  IV. Sequencing

ARMS-PCR

PCR-RFLP M

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

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

 Thalassemia /  Thalassemia Caused severe health problem!

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

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

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

serious anemia  HbH / α +/º Thalassemia  HbS /  Thalassemia  HbS / HbC  HbS / HbD  HbS / HbE  HbS / O Arab

Prenatal Diagnosis (PND)

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