For this, we isolated and cultured ECs derived from human vascular malformations carrying mutations in PIK3CA and TEK/TIE2 (Appendix Table S2), together spanning the genetic causes of more than 80% of low‐flow lesions in patients (Limaye et al, 2009, 2015; Castel et al, 2016; Castillo et al, 2016a). Here, TEK is linked to vascular malformation.