Which description best matches the genetics of sickle cell disease?

• A. Heterozygous HbS with mild symptoms
• B. Carrier state with no symptoms
• C. Homozygous HbS with red blood cell destruction and vascular blockage
• D. It is caused by a deficiency of iron

Answer: (C)

Sickle cell disease happens when a person inherits two copies of the mutated beta-globin gene (HbS). This causes hemoglobin to behave abnormally, especially when oxygen is low, making red blood cells become rigid and sickle-shaped. These misshapen cells are quickly destroyed, leading to hemolytic anemia, and they can also block small blood vessels, causing painful crises and organ damage from reduced blood flow. If someone has only one HbS allele, they’re usually asymptomatic or have only mild symptoms, which is why that carrier state isn’t the disease. Iron deficiency, on the other hand, is a separate cause of anemia and not what drives sickle cell disease. Therefore, the description that fits best is two HbS alleles with red blood cell destruction and vascular blockage.