duchenne muscular dystrophy (dmd) is a rare, x-linked recessive trait that causes muscular weakness, deterioration of muscle tissue, and loss of coordination. the allele for dmd is represented by xd and the normal allele is represented by xd. neither parent has dmd, but both of their sons express the trait. what are the most likely genotypes of the father's parents (ie. the son's paternal grandparents)? question 12 options: xdxd and xdy xdxd and xdy xdxd and xdy xdxd and xdy
