This is a study of the safety and tolerability of oral miransertib (MK-7075) administered to participants at least 2 years of age with phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-related overgrowth spectrum (PROS) or Proteus Syndrome (PS). This is an extension of other miransertib studies (MK-7075-002 \[NCT03094832\] or ArQule CU/EAP \[NCT03317366\]), and may also enroll participants who are approved for MK-7075-002 but have not yet started miransertib therapy.