We have shown that in mdx mice, which lack the protein dystrophin as in Duchenne muscular dystrophy that there are benefits in terms of left ventricular pressure-volume derived data with early beta- blocker treatment, though detrimental effects in the delta sarcoglycan deficient mouse model (Sgcd-/-, model for limb girdle muscular dystrophy type 2F) [6]. The gene discussed is DMD; the disease is Duchenne muscular dystrophy.