Question

A 22-year-old male reports to his eye doctor that he lost the center portion of the vision in his right eye over a week's time and 2 weeks later, the same thing happened in his left eye. He has two older brothers who had the same thing happen to them at age 21 and 23, and one older sister who had the same eye problems starting at age 24.

If the patient's sister has children, which of the following patterns will occur?
(A) All of her children will have the disease.
(B) None of her children will have the disease.
(C) Only her sons will have the disease.
(D) Only her daughters will have the disease.
(E) All of her children will be carriers of the disease.

Answer 1

The loss of central vision described is likely due to a genetic condition, and based on X-linked recessive inheritance patterns, if the condition in question is indeed X-linked, the patient's sister would have a 50% chance of passing the diseased allele to her sons and a 50% chance of passing the carrier status to her daughters.

Step-by-step explanation:

The condition described in the question, where a person loses the center portion of their vision, may suggest a genetic eye disorder rather than common vision problems such as myopia, hyperopia, or presbyopia. The pattern of loss of vision among the siblings, and the mention of a potentially inherited abnormality, indicates that this is likely related to a genetic condition. X-linked recessive disorders, such as red-green color blindness, commonly affect males more than females since males have one X and one Y chromosome while females have two X chromosomes. If the condition were X-linked, a female carrier would have a 50% chance of passing the recessive allele to her sons who would express the disease, and a 50% chance of passing the carrier status to her daughters.