What causes sickle cell trait?

What causes sickle cell trait?

• A. Inherit 2 HbS
• B. Inherit 1 HbS and 1 HbA
• C. Inherit 1 HbS and 1 HbC
• D. Inherit 2 HbA

Answer: (B)

Sickle cell trait occurs when you inherit one normal HbA gene and one sickle HbS gene. Being heterozygous for the sickle gene means most red blood cells still have enough normal hemoglobin to prevent widespread sickling, so carriers are usually asymptomatic. If you inherited two HbS genes, you’d have sickle cell disease because all hemoglobin tends to sickle under low oxygen. Inheriting HbS with HbC causes HbSC disease, a different condition. Two HbA genes would be normal hemoglobin with no trait.

Sickle cell trait occurs when you inherit one normal HbA gene and one sickle HbS gene. Being heterozygous for the sickle gene means most red blood cells still have enough normal hemoglobin to prevent widespread sickling, so carriers are usually asymptomatic. If you inherited two HbS genes, you’d have sickle cell disease because all hemoglobin tends to sickle under low oxygen. Inheriting HbS with HbC causes HbSC disease, a different condition. Two HbA genes would be normal hemoglobin with no trait.