Fig. 1. The proportion of female and male SMA pups born are not significantly different.

a) Of 23 litters (black), 11 litters contained one or more male SMA pups (dark gray) and 15 litters contained one or more female SMA pups (light gray). b) 21 of 82 (25.6%) female pups and 14 of 75 (18.7%) male pups were genetically confirmed to be SMA. Fisher’s exact contingency tests were applied to statistically compare proportions.