FZD4 and Familial exudative vitreoretinopathy: The identification of a heterozygous, dominant FZD4 variant (p.Pro251Arg) in a patient with familial exudative vitreoretinopathy (FEVR) raises questions about how the FZD5 p.Pro267Leu variant, affecting the same conserved amino acid, leads to a recessive phenotype.