DMD and Duchenne muscular dystrophy: The objective of this study was to analyze the impact of multiple variables, including the cumulative loss of shorter dystrophin isoforms (Dp140, Dp71, and Dp116), age, and corticosteroid treatment, on the variability of motor outcomes in a group of 138 genetically confirmed DMD patients from a developing country, Sri Lanka, a geographically defined population in South Asia.