SET and Neurodevelopmental delay: Variations of multiple subunits of PP2A- and PP2A-related proteins have been identified in NDD patients, including PP2A core-family-subunit-encoding genes [4] such as PPP2R1A [10], PPP2R5B, PPP2R5C, PPP2R5D [8,20,21] and PPP2CA [9], and PP2A regulator-encoding genes like SET, SETBP1, BOD1 and CIP2A [2].