Chapter 5, Problem 3CS

CASE STUDY| Doggone it!

A dog breeder discovers one of her male puppies has abnormal genitalia. After a visit to the veterinary clinic at a nearby university, the breeder learns that the dog's karyotype lacks a Y chromosome, but instead has an XX chromosome pair, with one of the X chromosomes slightly larger than usual (being mammals, male dogs are normally XY and females are XX). The veterinarian tells her that in other breeds, some females display an XY chromosome pair, with the Y chromosome being slightly shorter than normal. These observations raise several interesting questions:

Suppose you discover a female dog with a normal-sized XY chromosome pair. What kind of mutation might be involved in this case?