Thus, PTEN mutations in the endometrium can be a major driver of AH and appear to initiate the precursor of EEC, whereas a single mutation of Pik3caE545K [270] or Arid1a [273,274] is insufficient to induce endometrial hyperplasia, AH/EIN, or cancerous lesions. The gene discussed is ARID1A; the disease is exstrophy-epispadias complex.