Consistent with these observations, simultaneous neutralization of BMP9 and BMP10 in the postnatal retinal angiogenesis model [by injection of anti-BMP10 antibodies (Abs) into BMP9 knockout (KO) mice, or by co-injection of anti-BMP9 and anti-BMP10 Abs into wild type mice] led to hypervascularization17, 18, a vascular defect that was also observed in Acvrl1 or Eng conditional KO models and thus is reminiscent of HHT pathology29. This evidence concerns the gene ACVRL1 and hereditary hemorrhagic telangiectasia.