<qa>  What is the final objective of the study?The second objective is to use their well-characterized cardiac MRI biomarkers and define their sensitivity for detecting early cardiac involvement. The final objective is to use these validated cardiac MRI biomarkers to better understand the genotype-phenotype correlation in boys with DMD, which to date remain tenuous. The investigators propose a pilot study to explore cardiac genotype-phenotype correlations in boys with DMD and outlier phenotypes using approaches they have pioneered for skeletal muscle. 