thalassaemia by dr myo
TRANSCRIPT
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1. Reduced rate of production of one or more of the globin chains
QUANTITATIVE
Thalassaemias
2. Structural change in a globin chain leading to instability or abnormal oxygen transport
QUALITATIVE
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Thalassaemias
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Major - The severe transfusion-dependent Minor - The symptomless carrier states Intermedia - A group of conditions of
intermediate severity
This classification is retained because it has implications for both diagnosis and management
Clinical Classification
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Thalassemia major ◦ Requiring more than eight red blood cell
transfusions per year Thalassemia intermedia
◦ No or infrequent transfusions
Cunningham MJ, Macklin EA, Neufeld EJ, et al. Complications of beta-thalassemia major in North America. Blood 2004;104(1):34–9.
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According to which globin chain is produced in reduced amounts◦ α, β, δβ or εγδβ thalassemias
α0 or β0 thalassemias◦ No globin chain is synthesized at all
α+ or β + thalassemias◦ Some globin chain is produced but at a reduced
rate
Genetic Classification
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Alpha
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Beta
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Β Thalassaemia
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•Reduced rate of production of one or more of the globin chains
•Imbalanced globin chain synthesis
Thalassemia
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HbF level◦ Always elevated ◦ Heterogeneously distributed among the red cells.
β0-thalassaemia◦ No HbA,
β+-thalassaemia ◦ Level of HbF ranges from 30% to 90%.
HbA2 level ◦ Of no diagnostic value
Hemoglobin Changes
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MICROCYTHEMIA◦ Increased number of red cells which are smaller
than normal POIKILOCYTOSIS
◦ Abnormally shaped cells Target cells Irregularly distorted cells Punctate basophilia (basophilic stippling of red cells)
FBC Changes
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Serum ferritin – Increased % Saturation - Increased
IRON STUDIES
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HbE β-thalassaemia The commonest severe form of thalassaemia
in South-East Asia and parts of the Indian subcontinent.
There is usually severe anaemia and splenomegaly with typical thalassaemic bone changes
Diagnosis is confirmed by ◦ Only HbE and HbF on haemoglobin electrophoresis ◦ HbE trait in one parent and the β-thalassaemia trait
in the other
b-Thalassaemia in association withhaemoglobin variants
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Widening of the calvarium "hair-on-end" appearance.
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1. Carrier detection and genetic counselling about the choice of marriage partners
◦ If two β-thalassemia heterozygotes marry, ??
2. Prenatal counselling◦ when heterozygous mothers are identified
prenatally, the husbands may be tested If both are carriers, ??
Prevention and Treatment
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Should be offered only to couples at risk for having children with severe disease◦ Studies of globin chain synthesis in fetal blood
samples obtained by fetoscopy at 18–20 weeks’ gestation
◦ Analysis of fetal DNA obtained by CVS between weeks 9 and 12 of gestation Southern blot PCR
Prenatal Diagnosis
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Leukocyte-reduced red cell
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Young BRC’s Extension of transfusion interval
Cost vs. Benefit
Neocytes
• Neocytes have had a minor impact on the long-term management
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If possible, patients with thalassemia should receive blood matched for ◦ ABO◦ CcDdEe, and ◦ Kell antigens
Alloimmunization
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In the past◦ When annual transfusion requirements exceed
200–250 mL packed cells per kilogram body weight, splenectomy significantly reduces these requirements
In the modern era◦ With improved transfusion practices
Hypersplenism is reduced Many patients do not require splenectomy.
Splenectomy
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Infectious complications
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Prolonged parenteral infusion using portable ambulatory pumps
Deferoxamine
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Erratic compliance, especially in adolescents
Difficulty associated with long-term sc deferoxamine therapy
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Orally active iron chelating agents
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Long-term Monitoring
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Successful cure of b-thalassemia by bone marrow transplantation first was reported by Thomas and associates in 1982.
BMT
Thomas ED, Buckner CD, Sanders JE, et al. Marrow transplantation for thalassaemia. Lancet 1982;2(8292):227–9.
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The combination of ◦ Early diagnosis◦ Improvements in monitoring for organ
complications, and ◦ Advances in supportive care many patients who have severe thalassemia
syndromes to live productive, active lives well into adulthood
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