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]. The gene discussed is FZD4; the disease is Barth syndrome.