Which statement correctly distinguishes sickle cell disease from sickle cell trait?

Which statement correctly distinguishes sickle cell disease from sickle cell trait?

• A. Disease requires two recessive alleles (dd); trait is heterozygous (Dd).
• B. Disease has no symptoms; trait has severe symptoms.
• C. Disease is inherited maternally; trait is paternal.
• D. Disease affects only red blood cells; trait affects the entire body.

Answer: (A)

The key idea is how sickle cell disease and sickle cell trait differ by genotype and inheritance pattern. Sickle cell disease is seen when a person has two copies of the sickle allele (homozygous recessive, HbS/HbS). With both beta-globin genes carrying the sickle allele, there’s widespread production of abnormal hemoglobin, which tends to polymerize when oxygen is low and causes red blood cells to sickle, leading to anemia, painful crises, and organ complications. Sickle cell trait, on the other hand, is when a person is heterozygous (one normal allele and one sickle allele, HbA/HbS). The normal hemoglobin largely prevents the red cells from sickling under typical conditions, so carriers usually have no symptoms or only mild issues, though rare problems can occur under extreme stress or dehydration. Because this is an autosomal pattern, inheritance isn’t determined by whether the gene comes from the mother or father. Both conditions primarily affect red blood cells rather than the whole body in a direct sense.

The key idea is how sickle cell disease and sickle cell trait differ by genotype and inheritance pattern. Sickle cell disease is seen when a person has two copies of the sickle allele (homozygous recessive, HbS/HbS). With both beta-globin genes carrying the sickle allele, there’s widespread production of abnormal hemoglobin, which tends to polymerize when oxygen is low and causes red blood cells to sickle, leading to anemia, painful crises, and organ complications.

Sickle cell trait, on the other hand, is when a person is heterozygous (one normal allele and one sickle allele, HbA/HbS). The normal hemoglobin largely prevents the red cells from sickling under typical conditions, so carriers usually have no symptoms or only mild issues, though rare problems can occur under extreme stress or dehydration.

Because this is an autosomal pattern, inheritance isn’t determined by whether the gene comes from the mother or father. Both conditions primarily affect red blood cells rather than the whole body in a direct sense.