For example, we found that B3GALT5, a putative inhibitor of SHH signaling, has a fold change of 0.92 in TcMAC21, despite this model having two copies of mouse B3galt5 and one copy of human B3GALT5. Moreover, although our SHH screen and RNA-seq data support an oligogenic or polygenic explanation for cerebellar hypoplasia in mouse models, testing this hypothesis by returning candidate genes to disomy would be technically challenging owing to difficult husbandry, relatively subtle phenotypes and high interindividual variability (Roper and Reeves, 2006; Roper et al., 2006b; Shaw et al., 2020). Here, B3GALT5 is linked to Cerebellar hypoplasia.