Collagen alpha-1(, Xenopus/Amphibian,VIII) chain (endostatin) plays a major role in determining the retinal structure as well as in the closure of the neural tube. Endostatin potently inhibits endothelial cell proliferation and angiogenesis by binding to the heparan sulfate proteoglycans involved in growth factor signaling. Defects in endostatin are a cause of Knobloch syndrome (KNO). KNO is an autosomal recessive disorder defined by the occurrence of high myopia, vitreoretinal degeneration with retinal detachment,Mouse,acular abnormalities and occipital encephalocele.