Question

The pedigree to the right is tracking a disease through three generations. Is this disease autosomal recessive or autosomal dominant? Why?

Answer 1

The disease in the pedigree is autosomal recessive because individuals with the condition (genotype aa) are present only when both parents carry the mutant gene.

Carriers (genotype Aa) do not show symptoms, which is characteristic of autosomal recessive inheritance.

Step-by-step explanation:

The pedigree provided is tracking the inheritance patterns and genotypes of a specific disorder across three generations.

Given that the disorder appears in individuals who both parents are carriers, and that affected individuals are shown in blue with the genotype aa, this suggests that the disorder is autosomal recessive.

Autosomal recessive inheritance requires an individual to inherit two copies of the mutant gene, one from each parent, to express the phenotype of the disorder.

Therefore, carriers of an autosomal recessive condition, who have the genotype Aa, do not show symptoms because their unaffected gene compensates for the recessive allele. Tay-Sachs disease and cystic fibrosis are examples of autosomal recessive genetic disorders.