photo.jpg

## Sickle Cell Hemoglobinopathies ### Hemoglobin S (Hb S) - most common abnormal hemoglobin - Normal glutamic acid at 6th position in the β chain is replaced by valine - **Results in:** - Altered solubility - Altered ability to withstand oxidation - Instability - Increased propensit...

## Sickle Cell Hemoglobinopathies ### Hemoglobin S (Hb S) - most common abnormal hemoglobin - Normal glutamic acid at 6th position in the β chain is replaced by valine - **Results in:** - Altered solubility - Altered ability to withstand oxidation - Instability - Increased propensity for methemoglobin production - Increased oxygen affinity Sickle Cell Anemia is the homozygous state of Hb S (also called: Sickle cell disease (SCD) or Hb SS disease), whereas sickle cell trait is the heterozygous state with one sickle gene and one normal hemoglobin gene (Hb AS). Usually with no symptoms but occasional hematuria occurs as a complication of the disorder. ### Sickle Cell Trait vs. Disease #### Trait: - Typically no health consequences or symptoms #### Disease: - Significantly impacts a person's health and causes many symptoms ### Sickle Cell Disease - Sickle cell disease is an autosomal recessive inherited defect caused by sickle hemoglobin (Hb S) - Erythrocytes become elongated and sickle shaped, removed from the circulation and destroyed at increasing rates (10-20 d) leading to anemia. - The disease is chronic and lifelong - Life span is 40 years in average. - If one parent has sickle cell anemia and other is normal, all children will have sickle cell trait. - If one parent has sickle cell anemia and other has sickle cell trait, there is 50% chance of either with each pregnancy. ### Pathophysiology - caused by a point mutation in the β-globin chain of hemoglobin resulting replacement ### Factors affecting sickle cell crisis - The degree of dehydration - pH: low pH favours sickling - Dehydration - The concentration of oxygen, less oxygen favors sickling - Heredity - Vaso-occlusive crisis: - Increase in blood viscosity - Hemolytic crisis: - Acute accelerated red cell destruction - Infection: - Abnormal immune response - Bacterial infection - Streptococcal infection - Aplastic crisis: - Causes bone marrow suppression - Decrease in red blood cell production