PPP2R1A and Intellectual disability: While PPP2R1A variants (Houge-Janssens syndrome 2, OMIM #616362) are associated with intellectual disability, hypotonia, language impairment, epilepsy, microcephaly, and brain malformations, variants in PPP2R1B (encoding the alternative Aβ scaffold) and PPP2R5D (encoding the B56δ regulatory subunit, Houge-Janssens syndrome 1) produce remarkably similar clinical features including intellectual disability, macrocephaly, hypotonia, and autism [9].