Association of <i>DMD</i> Gene Variant Classes With Motor Outcomes in a Drug Registration Clinical Trial Setting

The large variation in baseline motor function in young, steroid-naïve patients with DMD is only minimally explained by different gene variant classes. While there is strong literature support for 3' variants leading to a more severe motor and cognitive DMD phenotype, we found this variant class under-represented in our clinical trials. This suggests that they may fail inclusion criteria (failure to follow commands; poor motor function). Subgroup analyses in DMD clinical trials at a young age range based on gene variant class may not reveal significant differences and would be relatively noninformative.