COL4A1 and skeletal muscle disorder: ICH severity in untreated Col4a1+/Δex41 mice was similar to that observed in untreated Col4a1+/Δex41 mice at 2MO (exercised) and 8MO (unexercised), and both ICH and skeletal myopathy were significantly suppressed in Col4a1+/Δex41 mice provided with 4PBA from E9.5 to 3MO (Fig. 3A-C).