De novo partial deletions, translocations, missense, and truncating mutations in TCF4 have also been identified in MMID patients without the typical characteristics of PTHS (8, 9, 10, 11, 12, 13) and one missense mutation in TCF4 has been linked to a Rett-like syndrome (RTT-like) (14). Here, TCF4 is linked to Pitt-Hopkins syndrome.