Roberts Supplemental Figure 1 Plethysmography Mouse Count fTVbMVbPenhPAURpefCompPIFbPEFbTiTeEF50TrTbodyTcRHRinx 4 Weeks WT D24Average SEM Sgcg -/- D29Average SEM Mdx10Average SEM Weeks WT D26Average SEM Sgcg -/- D29Average SEM Mdx20Average SEM Weeks WT D20AverageN/A SEMN/A Sgcg -/- D27Average SEM Mdx10Average SEM Weeks WT D24Average SEM Sgcg -/- D26Average SEM Mdx8Average SEM

Morphological Parameters Mouse Count LVAWd (mm) LVAWs (mm) LVPWd (mm) LVPWs (mm) LVIDd (mm) LVIDs (mm)RWT LV mass (mg) Mouse Wt (g) Diastolic Parameters E (mm/ sec) A (mm/ sec)E/A E DT (msec) IVRT (msec) E' (mm/ sec) A' (mm/ sec)E'/A'E/E'EDV (uL) Systolic Parameters EF (%)FS (%)ESV (uL) SV (  L) CO (mL/min)HR S' (mm/ sec)PA VTIPA ETPA ATPA AT/ET 4 Week WT D20AverageN/A WT D2AverageN/A WT D2AverageN/A SEMN/A SEMN/A SEMN/A Sgcg -/- D28Average KO D2Average KO D2Average SEM SEM SEM Mdx10Average MdxAverage MdxAverage SEM SEM SEM Week WT D24Average WT D2Average WT D2Average N/A SEM SEM SEM N/A Sgcg -/- D223Average KO D2Average KO D2Average SEM SEM SEM Mdx10Average MdxAverage MdxAverage SEM SEM SEM Week WT D26Average WT D2Average WT D2Average SEM SEM SEM Sgcg -/- D213Average KO D2Average KO D2Average SEM SEM SEM Mdx10Average MdxAverage MdxAverage SEM SEM SEM Week WT D210Average WT D2Average WT D2Average SEM SEM SEM Sgcg -/- D25Average KO D2Average KO D2Average SEM SEM SEM Mdx8Average MdxAverage MdxAverage SEM SEM SEM Roberts Supplemental Figure 2 Echocardiography