PIK3CA and angioosteohypertrophic syndrome: While the pathogenesis of these syndromes remains unclear, KTS is associated with mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene, which encodes for the catalytic subunit of the phosphatidylinositol 3-kinase (PI3K) enzyme responsible for activating the protein kinase B (AKT)-mammalian target of rapamycin (mTOR) signaling cascade [54].