This finding is consistent with the lack of germline PIK3CA mutations in cancer patients and the observation that PIK3CA mutations associated with PIK3CA-related overgrowth spectrum (PROS) are acquired post-zygotically and are not inherited [16,17,19,20,72] and demonstrates that activating mutations in PIK3CA are not compatible with germline transmission. The gene discussed is PIK3CA; the disease is cancer.