FZD4 and Norrie disease: Norrie disease and familial exudative vitreoretinopathy (FEVR) are both hereditary eye disorders characterised by aberrant and incomplete retinal vascular development, and are associated with mutations in Fzd4 (Junge et al., 2009), which has been linked to ERG expression in other angiogenesis-associated disease (Gupta et al., 2010).