Inherited disorders of haemoglobins Flashcards
What is the difference between sickle cell disease and thalassaemia?
Sickle cell disease –> changes to the globin chain amino acid sequence resulting in variant hb (QUALITATIVE)
Thalassaemia –> Complete or partial reduction of a globin chain (QUANTITATIVE)
What is the genetic change in sickle cell disease?
Autosomal recessive.
Substitution of valine for glutamic acid at position 6 of the β globin chain.
Homozygotes –> HbSS (HbS –> ααSS)
Heterozygotes –> HbAS (Both HbA and HbS)
What are some features of sickle cell trait?
1) Carrier state
2) Partial protection against falciparum malaria
3) Usually asymptomatic with normal life expectancy
4) Risk of baby with HbSS
5) Increased risk of some diseases: Renal disease, thromboembolism, splenic infarction, and pregnancy complications
What are reticulocytes?
Immature red blood cells
What are some features of sickle cell disease?
1) Reduced deformability of RBCs which results in venocclusion
2) Reduced life span of RBCs due to haemolysis –> Increased bilirubin (jaundice)
3) Compensatory increase in RBC production leads to reticulocytosis and potential folate deficiency
What is a vaso-occlusive crises?
Most common manifestation of sickle cell disease.
It occurs when the microcirculation is obstructed by sickled RBCs, causing ischemic injury to the organ supplied and resultant pain.
Normally resolve within 1-7 days.
What is acute chest syndrome?
A vaso-occlusive crisis of the pulmonary vasculature commonly seen in people with sickle cell anaemia.
What is an aplastic crisis?
Temporary cessation or red blood cell production with a corresponding decrease in reticulocyte count.
Approx. 40% are thought to be caused by parvovirus B19 infection.
What are some complications of an acute vaso-occlusive/ SCD crisis?
1) Sepsis
2) Renal
3) Venous thromboemolism (VTE)
4) Acute chest syndrome
What medication is used to treat patients with severe recurrent painful crises or episodes of acute chest syndrome?
Hydroxycarbamide (hydroxyurea)
4 beta globin chains….
Hb H
4 gamma globin chains…..
Hb Barts
What is extramedullary hematopoiesis?
Hematopoiesis occurring in organs outside of the bone marrow.
It occurs in diverse conditions, including fetal development, normal immune responses, and pathological circumstances.
What are the consequences of iron overload from blood transfusions?
1) Contributes to growth failure
2) Multiple endocrine dysfunctions
3 Cardiac & hepatic toxicity
What is desferrioxamine used for?
Subcutaneous iron chelation infusions
