Murine models of Col4a1 and Col4a2 mutations faithfully replicate Gould syndrome and allelic heterogeneity was shown to modulate the severity of ICH in an allelic series of Col4a1 and Col4a2 mutant mice (Jeanne and Gould, 2017; Labelle-Dumais, 2019; Kuo et al., 2014). Here, COL4A2 is linked to COL4A1/A2-related disorder.