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How is sickle-cell disease inherited from parents?
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blood disease
Peripheral blood smear revealing histopathologic features indicative of a blast crisis in a case of chronic myelogenous leukemia (CML). Blast crisis occurs when one-fifth to one-third of the cells in the blood or bone marrow are immature blood cells, or blast cells. This phase of CML is characterized by fever, weakness, and an enlarged spleen.
Sickle-cell disease is an autosomal recessive disorder, meaning it is inherited when a child receives a mutant hemoglobin gene from both parents.1
The inheritance process works as follows:
- Carrier Parents: If both parents are carriers (heterozygotes who possess one normal gene and one mutant gene), they are typically unaffected by the disease. However, for each pregnancy, there is a 1 in 4 chance that the child will inherit the mutant gene from both parents and develop sickle cell anemia.12
- Carrier and Affected Parent: If one parent is a carrier and the other is affected by the disease, there is a 1 in 2 chance for each pregnancy that the child will have the condition.1
In the homozygous state—where an individual inherits the variant hemoglobin S (HbS) gene from both parents—the red blood cells become rigid and sickle-shaped, leading to the symptoms associated with the disease. Individuals who inherit the gene from only one parent are considered to have the sickle cell trait; they are generally asymptomatic but can pass the gene to their offspring.23