Question

red - green colorblindness is a recessive sex - linked disorder. if two parents with normal vision have a daughter with red - green colorblindness, what is the most likely explanation for how the daughter acquired the disorder?
the parents are both carriers for red - green colorblindness, even though neither shows the trait.
the daughter experienced a mutation as a zygote that resulted in red - green colorblindness.
the father experienced a mutation in his eye cells that caused red - green colorblindness, and the disorder was passed to his daughter.
the daughter is a carrier for red - green colorblindness but shows the trait because she has two x chromosomes.

Explanation:

Red - green colorblindness is a recessive sex - linked disorder. Let's analyze each option:

• Option 1: If both parents are carriers (father: \(X^{C}Y\), mother: \(X^{C}X^{c}\)), they can pass on two recessive alleles (\(X^{c}\)) to their daughter (\(X^{c}X^{c}\)). This is a common way for a recessive disorder to be inherited.
• Option 2: While mutations can occur, it is less likely compared to the inheritance from carrier parents.
• Option 3: Mutations in somatic cells (eye cells) are not passed on to offspring. Only mutations in germ cells (sperm or egg) can be inherited.
• Option 4: A carrier (\(X^{C}X^{c}\)) does not show the trait. For a female to show the trait, she must have two recessive alleles (\(X^{c}X^{c}\)).

Answer:

The parents are both carriers for red - green colorblindness, even though neither shows the trait.