Tracie just gave birth to her first child, byron, and after much testing, doctors discovered byron has muscular dystrophy.
neither tracie nor her husband displays any signs of muscular dystrophy. how can you explain this?
muscular dystrophy is a phenotype in both parents.
muscular dystrophy is a genotype in both parents.
muscular dystrophy runs in the mother's family.
muscular dystrophy is a trait in both parents.

Muscular dystrophy runs in the mother's family.

Explanation:

Muscular dystrophy is able to pass down from the parents of a child. Females have two X genes that are able to make the dystrophin protein, but when one of their X genes becomes a carrier for muscular dystrophy, they can pass it down if that gene is the gene given to their child, which can become dangerous especially if the child is male. Males have an X and a Y gene, and depending on which gene is given to the child, the child will be either male or female. When the Y gene is given from the father and the defective X gene is given from the mother, the male child doesn't have another X gene to make the protein dystrophin and therefore is at risk for muscular dystrophy.

I'm not great at explaining things, I hope this helps :)