In earlier mouse models of MVID, which were generated by Rab8a, Rab11a and Cdc42 mutations, or combinations thereof, the animals failed to thrive due to unresolved causes (Feng et al., 2017; Melendez et al., 2013; Sakamori et al., 2012; Sato et al., 2007; Sobajima et al., 2014; Yu et al., 2014). Here, RAB8A is linked to microvillus inclusion disease.