16. Hemoglobinopathies
Sickle cell Disease
• Sickle cell anemia is an autosomal recessive disease that results from the
substitution of valine for glutamic acid at position 6 of the beta-globin
gene.
• Patients who are homozygous for the HbS gene have sickle cell disease.
Patients who are heterozygous for the HbS gene have sickle trait
• Crisis in sickle cell disease:
1. Vaso-occlusive crisis
2. Acute Chest Syndrome
3. Sequestration crisis
4. Aplastic Crisis
17.
18. • Thalassemia
• caused by defects in the globin gene, are the most common
monogenic disease
19.
20. G6PD deficiency Anemia
• Glucose-6- phosphate dehydrogenase (G6PD) deficiency is the most common red cell enzyme
deficiency. It is an X-linked recessive disease with full expression in affected males
• After an oxidant exposure, hemoglobin is oxidized to methemoglobin and denatured to form
intracellular inclusions also known as Heinz bodies.
• These Heinz bodies get attached to the red cell membrane and aggregate intrinsic membrane
proteins such as band 3.
• Reticuloendothelial cells detect these membrane changes as antigenic sites and ingest a part of
the red cell.
• This partly phagocytosed cell, called 'bite’ cell, has a shortened half-life.
• Drugs that cause oxidant formation are:
• Sulfonamides
• Antimalarials: primaquine, quinine
• Aspirin
• dapsone.