COL4A1 and myopathy: Notably, ICH and myopathy in approximately half of the Col4a1+/Δex41 mice from the cohort provided with 25 mM 4PBA from birth were milder than the mildest case of the untreated Col4a1+/Δex41 cohort; however, the population showed broad ranges of severities (Fig. 4A-C).