FZD4 and Familial exudative vitreoretinopathy: In particular, dystrobrevin alpha, encoded by DTNA, is causally involved in Barth syndrome, a severe infantile cardiomyopathy [54], and Frizzled-4 protein, a receptor for Wnt proteins, encoded by FZD4, is causally involved in familial exudative vitreoretinopathy leading to an avascular peripheral retina [55].