Corneal astigmatism is a relatively rare inherited condition that causes blurry vision if not corrected. It is a dominant Mendelian trait. (Mendelian means it obeys Mendel's Principle of Segregation.) Suppose Rex has an astigmatism but his mother did not. Which of the following statements follows from this information, assuming no mutation? (NOTE: This assumption is almost always true--mutations are far more rare than most people believe.)

• Rex's mother is homozygous recessive.
• The probability that Rex's brother has astigmatism is 1/4.
• The probability that Rex's sister has astigmatism is 3/4.
• We cannot know Rex's father's genotype for certain.
• Rex is homozygous recessive.
• Rex's mother is heterozygous.
• We cannot know Rex's mother's genotype for certain.
• Rex's father has astigmatism.
• Rex's father is homozygous recessive.
• Rex's father has normal vision.
• Rex is homozygous dominant.
• The probability that Rex's brother has astigmatism is 1/2.
• We cannot know the probability that Rex's sister would have astigmatism without more information.
• Rex's father is homozygous dominant.
• Rex is heterozygous.
• Rex's father is heterozygous.
• We cannot know Rex's genotype for certain.

Rex's mother is homozygous dominant

Answer rating: 100% (QA)

It shows that the disease is an autosomal dominant disorder Rex has astigm... View the full answer