TCF4 and Pitt-Hopkins syndrome: Given the observation that patients in our study did not share the distinctive features of Pitt Hopkins syndrome (Table 1), the syndromic form of ID associated with heterozygous TCF4 mutations, and the potential for translocated chromosomal segments to have altered gene expression [37], we used quantitative RNA sequencing to test for gene expression changes on chromosomes 14 and 18 (see Methods).