Somatic mutations in TEK, the gene encoding endothelial cell tyrosine kinase receptor TIE2, cause more than half of sporadically occur- ring unifocal venous malformations (VMs). Here, we report that somatic mutations in PIK3CA, the gene encoding the catalytic p110a subunit of PI3K, cause 54% (27 out of 50) of VMs with no detected TEK mutation. The hotspot mutations c.1624G>A, c.1633G>A, and c.3140A>G (p.Glu542Lys, p.Glu545Lys, and p.His1047Arg), frequent in PIK3CA-associated cancers, overgrowth syndromes, and lymphatic malformation (LM), account for >92% of individuals who carry mutations. Like VM-causative mutations in TEK, the PIK3CA mutations cause chronic activation of AKT, dysregulation of certain important angiogenic factors, and abnormal endothelial cell morphology when expressed in human umbilical vein cells (HUVECs). The p110a-specific inhibitor BYL719 restores all abnormal phenotypes tested, in PIK3CA- as well as TEK mutant HUVECs, demonstrating that they operate via the same pathogenic path- ways. Nevertheless, significant genotype-phenotype correlations in lesion localization and histology are observed between individuals with mutations in PIK3CA versus TEK, pointing to gene-specific effects
Limaye, N., Kangas, J., Mendola, A., Godfraind, C., Schlögel, M., Helaers, R., Eklund, L., Boon, L., & Vikkula, M. (2015). Somatic Activating PIK3CA Mutations Cause Venous Malformation. American Journal of Human Genetics, 97(6), 914-921. https://doi.org/10.1016/j.ajhg.2015.11.011 (Original work published 2015)