Although left ventricular systolic volume was significantly larger in mdx-ApoE mice compared to mdx mice at 7 months of age on Wester diet, histological observation of cardiac muscle revealed similarly minor cardiac fibrosis in both mdx and mdx-ApoE mice compared to controls by 7 months of age on Western diet (Additional file 4: Figure S3E). The gene discussed is APOE; the disease is fibrosis.