Question

Which of the fol lowing statements accurately describes the pattern of inheritance that occurs with autosomal dominant traits?

• A. If only one parent is affected, only half of their offspring will inherit the trait.
• B. If only one parent is affected, all of their offspring will inherit the trait.
• C. Both parents must be affected for any of their offspring to inherit the trait.
• D. Both parents must be homozygous for the trait for any of their offspring to inherit the trait.
• E. None of the statements are true of the pattern of inheritance that occurs with autosomal dominant traits.

Answer 1

Answer: (A)

If only one parent is affected, only half of their offspring will inherit the trait.

Autosomal dominant traits are the characters that are transmitted via autosomes. Autosomes are the chromosomes other than the sex chromosomes. Suppose a trait is controlled by the autosomal gene designated as A'. Since it is dominantly expressed, then the affected individual will have the genotype A'A and the one with normal genotype would be AA.

If one parent is affected then the cross will be as follows:

A'A X AA

This will result in the genotypes A'A and AA in the ratio 1:1 i.e. half of the offspring will be affected and inherit the trait.

So, the correct answer is 'If only one parent is affected, only half of their offspring will inherit the trait'.