Question

Glaucoma is a leading cause of blindness. Studies have linked a common form of glaucoma to three genes and more than 20 genetic loci. Which best describes glaucoma?

a. . a recessive trait that requires multiple recessive alleles to be expressed
b. . a polygenic trait that is influenced by the number of alleles present
c. . a codominant trait that is expressed more often when more dominant alleles are present
d. . a dominant trait that depends on the presence of only one of many dominant alleles

Answer 1

The answer is b. a polygenic trait that is influenced by the number of alleles present.

There are three genes linked to a common form of glaucoma, so it must be the polygenic (meaning more than one gene included) trait. The polygenic traits are influenced by the number of alleles. In this case, there are more than 20 genetic loci which means there must be a great number of alleles for all loci.

Answer 2

The answer to the question given is letter b. a polygenic trait that is influenced by the number of alleles present.

Large multiplex families suitable for linkage analysis are typically affected by early-onset forms of glaucoma inherited as Mendelian dominant or recessive traits.
>A polygenic trait is one whose phenotype is influenced by more than one gene.
>A polygenic inheritance is one genetic mechanism giving us a continuous range of possibilities.