a. In humans a form of muscular dystrophy is a disease which begins in childhood with a gradual wasting away of the muscles and almost always ends in death in the early teens. This disease is due to an x-linked recessive allele.
a. Explain why it almost never occurs in girls.

b. A couple has a family of three daughters without muscular dystrophy and three sons between the ages of eight and fifteen, and their youngest son has muscular dystrophy. What are their chances of producing another afilicted child? (Here, you have to calculate in the chances of producing a male vs. female child. Assume that 50% of children will be female, and 50% will be male.)

c. If the children without muscular dystrophy (see part b.) married individuals without MD and with no family history of MD, could some of the offspring of these marriages be afflicted with uscular dystrophy? Explain your answer.