Why Did Garrod Define Alkaptonuria as a Recessive Genetic Disease

Question

Why did Garrod define alkaptonuria as a recessive genetic disease?
A)It is expressed in male members of an affected family.
B)It is expressed in all members of an affected family.
C)It is expressed under certain environmental conditions.
D)It is expressed when two alleles for the disease are present.
E)It is expressed when one of the two alleles carries the disease trait.

Accepted Answer

Garrod defined alkaptonuria as a recessive genetic disease because it is only expressed when two alleles for the disease are present. Alkaptonuria is caused by a mutation in the HGD gene, and individuals must inherit two copies of the mutated gene to develop the disease.