Question

examine the pedigree showing the inheritance of the sickle cell trait in a family. which option correctly describes the mode of inheritance for sickle cell anemia? x - linked recessive recessive dominant x - linked dominant (with a pedigree image showing father, mother, and four children, and a key for sickle hemoglobin gene and normal hemoglobin gene)

Explanation:

1. Analyze the pedigree: Both parents have the sickle cell trait (heterozygous, carrying one sickle hemoglobin gene and one normal).
2. One child has sickle cell anemia (homozygous for the sickle gene), while others have the trait or no trait.
3. For a recessive disorder, affected individuals (with the disease) have two recessive alleles, and carriers (with the trait) have one recessive and one dominant. Since parents are carriers (trait) but not affected, and a child is affected, this fits recessive inheritance.
4. It is not X - linked because the inheritance pattern (affected child, carrier parents) doesn't show X - linked patterns (e.g., more males affected in X - linked recessive, or dominant inheritance patterns). Also, dominant would mean affected parents would likely have more affected children, which isn't the case here.

Answer:

recessive