In humans, one form of muscular dystrophy (Emery–Dreifuss muscular dystrophy) is x-linked. A young man, Joe, has muscular dystrophy but his parents do not.
a) What are the genotypes of Joe and his parents?
b) What are the possible genotypes of Joe’s grandparents,
c) If Joe’s parents have additional children, what are the probabilities that Joe’s future sisters and brothers will have muscular dystrophy?
d) Of Joe’s 4 grandparents, only his father’s father has muscular dystrophy. What are the possible genotypes of the 4 grandparents? From which of the grandparents could Joe have inherited muscular dystrophy?