ATM and telangiectasis: All the five patients showed bulbar conjunctival telangiectasia, which may be due to the increased expression of hypoxia-inducible factor 1 (HIF-1) after ATM protein loss, then the overexpression of HIF-1 promotes the expression of the target gene involved in angiogenesis (such as vascular endothelial growth factor), ultimately increase angiogenesis (22).