Familial exudative vitreoretinopathy (FEVR, MIM

133780) is a hereditary disorder resulting from a develop-mental anomaly of the retinal vessels that may be stationary or progressive [1]. Patients with FEVR exhibit highly vari-able manifestations, ranging from asymptomatic to complete blindness. Progressive vascular anomalies impair vision due to various complications such as retinal neovascularization, exudates, fibrovascular proliferation, retinal folds, optic disc dragging, and retinal detachment [2]. Some minimally affected individuals may be detected only with fluorescein angiography of the peripheral retina, which exhibits avascu-larization and a nonperfusion zone [3]. Mutations in at least four genes have been identified as responsible for autosomal dominant (the FZD4, LRP5, and TSPAN12 genes) [4–7], autosomal recessive (the LRP5 gene) [8], or X-linked (the NDP gene) [9,10] FEVR. The encoded proteins of these four genes are involved in the wingless (Wnt) signaling pathway, which monitors retinal vascular development [7,11–14]. To date, several mutations have been identified in the four genes in patients with FEVR [15]. However, such studies in Chinese patients are limited [16,17]. To better understand the molecular defects underlying FEVR in the Chinese population, we performed a mutation screening of FZD4 and LRP5 in 49 Chinese families with FEVR and identified mutations in 11 families. METHODS Patients: Written informed consent in accordance with the guidelines of the Declaration of Helsinki was obtained from the participating individuals or their guardians before the clinical data and genomic samples were collected. Ethical approval was provided by the Internal Review Board of th