Rosenfeld JA, Leppig K, Ballif BC, Thiese H, Erdie-Lalena C, Bawle E, Sastry S, Spence JE, Bandholz A, Surti U, Zonana J, Keller K, Meschino W, Bejjani BA, Torchia BS, Shaffer LG. Genotype-phenotype analysis of TCF4 mutations causing Pitt-Hopkins syndrome shows increased seizure activity with missense mutations. Genet Med. 2009 Nov; 11(11):797-805.