COL4A2 and muscular disease: Mice heterozygous for a Col4a1 splice site mutation that causes skipping of exon 41 (Col4a1+/Δex41) recapitulate the pathophysiological hallmarks of cerebrovascular and muscular disease observed in patients with COL4A1 and COL4A2 mutations, and thus constitute a powerful pre-clinical model to test the efficacy and treatment parameters of potential therapeutic agents (Gould et al., 2005, 2006; Kuo et al., 2012).