PIK3CA and meningioma: While the fundamental role of biallelic NF2 loss in meningiomas from NF2 patients and approximately 50% of sporadic meningiomas has long been recognized [27, 28], a spectrum of recurrent oncogenic driver mutations including in SMO, KLF4, TRAF7, AKT1, or PIK3CA has more recently been identified, and are mutually exclusive with NF2 alterations.