Previously, we successfully demonstrated that Col4a1 and Col4a2 mutant mice can recapitulate pathophysiological hallmarks of Gould syndrome, including ICH, whose severity was modulated by allelic heterogeneity (Jeanne et al., 2015; Jeanne and Gould, 2017). Here, COL4A2 is linked to COL4A1/A2-related disorder.