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Pathology - Sickle cell disorders
Definition: A collection of hereditary red blood cell diseases resulting from HbS.
Epidemiology • Most commonly observed in individuals of African heritage and regions with current or historical malaria endemicity. The mutant gene persists as heterozygote carriers are safeguarded against the severe effects of Plasmodium falciparum malaria.
Genetics: HbS results from a point mutation in the β-globin gene located on chromosome 11, leading to a substitution of glutamic acid with valine. Heterozygotes are characterized by possessing sickle cell trait. • Homozygotes experience sickle cell disease or sickle cell anemia. Pathogenesis HbS exhibits a solubility that is 50 times inferior to that of HbA. Under low oxygen tension, HbS polymerizes into rod-like aggregates, resulting in the red blood cell adopting a sickled morphology.
Presentation • Individuals possessing sickle cell trait do not experience sickling due to the presence of normal HbA protein, which diminishes the aggregation of HbS. Patients are typically asymptomatic and exhibit normal hemoglobin levels. They are, nonetheless, genetically significant as carriers of the sickle cell allele. Individuals with sickle cell disease typically manifest symptoms at the age of two, after depleting most of their HbF, resulting in nearly all hemoglobin being HbS. Their red blood cells undergo sickling in venous blood, resulting in chronic hemolysis and episodes of vascular crises.
Complete blood count: Decreased hemoglobin, often ranging from 7 to 9 g/dL.
Peripheral blood smear • Sickle-shaped erythrocytes and their variations are present. • In adults, evidence of hyposplenism is present, shown by target cells, Howell–Jolly bodies, and Pappenheimer bodies. Diagnosis • The sickle cell solubility test serves as an effective screening method wherein a reducing agent is included into hemoglobin recovered from erythrocytes. HbS rapidly precipitates, resulting in a turbid solution. Definitive diagnosis necessitates Hb electrophoresis, which reveals a singular predominant HbS band and the absence of normal HbA.
Prognosis: Patients with sickle cell disease exhibit a markedly reduced lifetime. The median age of death is approximately 42 years for males and 48 years for women.
Complications associated with sickle cell disease Childhood: Hand-foot syndrome. • Splenic sequestration crisis. • Cerebrovascular accident. Subsequent years • Bacterial infections. • End-stage renal disease. • Priapism. • Ulceration of the lower extremities. • Pigmentary gallstones. • Avascular necrosis of the femoral head. • Pulmonary syndrome.
Definition: A collection of hereditary red blood cell diseases resulting from HbS.
Epidemiology • Most commonly observed in individuals of African heritage and regions with current or historical malaria endemicity. The mutant gene persists as heterozygote carriers are safeguarded against the severe effects of Plasmodium falciparum malaria.
Genetics: HbS results from a point mutation in the β-globin gene located on chromosome 11, leading to a substitution of glutamic acid with valine. Heterozygotes are characterized by possessing sickle cell trait. • Homozygotes experience sickle cell disease or sickle cell anemia. Pathogenesis HbS exhibits a solubility that is 50 times inferior to that of HbA. Under low oxygen tension, HbS polymerizes into rod-like aggregates, resulting in the red blood cell adopting a sickled morphology.
Presentation • Individuals possessing sickle cell trait do not experience sickling due to the presence of normal HbA protein, which diminishes the aggregation of HbS. Patients are typically asymptomatic and exhibit normal hemoglobin levels. They are, nonetheless, genetically significant as carriers of the sickle cell allele. Individuals with sickle cell disease typically manifest symptoms at the age of two, after depleting most of their HbF, resulting in nearly all hemoglobin being HbS. Their red blood cells undergo sickling in venous blood, resulting in chronic hemolysis and episodes of vascular crises.
Complete blood count: Decreased hemoglobin, often ranging from 7 to 9 g/dL.
Peripheral blood smear • Sickle-shaped erythrocytes and their variations are present. • In adults, evidence of hyposplenism is present, shown by target cells, Howell–Jolly bodies, and Pappenheimer bodies. Diagnosis • The sickle cell solubility test serves as an effective screening method wherein a reducing agent is included into hemoglobin recovered from erythrocytes. HbS rapidly precipitates, resulting in a turbid solution. Definitive diagnosis necessitates Hb electrophoresis, which reveals a singular predominant HbS band and the absence of normal HbA.
Prognosis: Patients with sickle cell disease exhibit a markedly reduced lifetime. The median age of death is approximately 42 years for males and 48 years for women.
Complications associated with sickle cell disease Childhood: Hand-foot syndrome. • Splenic sequestration crisis. • Cerebrovascular accident. Subsequent years • Bacterial infections. • End-stage renal disease. • Priapism. • Ulceration of the lower extremities. • Pigmentary gallstones. • Avascular necrosis of the femoral head. • Pulmonary syndrome.
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