Sherk and Williams [157] noted an increased number of large vessels crossing the optic disk in DS patients, while Parsa and Almer [158] suggested that the abnormal optic disk vessels in DS eyes may be due to an extra copy of the chromosome 21-encoded gene endostatin, a potent inhibitor of angiogenesis, endothelial cell proliferation, and migration. This evidence concerns the gene COL18A1 and Dravet syndrome.