Transcription factor 7 like 2 (TCF7L2, also known as TCF4) is a Wnt signaling pathway transcription factor involved in the regulation of numerous Wnt targeted genes. TCF4 is critical in the vertebrate intestinal epithelium, where TCF4-β-catenin complexes are necessary for the maintenance of a proliferative compartment, and their abnormal formation initiates tumorigenesis. β-catenin, an upstream protein of TCF4, accumulates in the cytoplasm, then translocates to the nucleus to activate the β-catenin/T-cell factor/lymphoid enhancer factor (TCF/LEF) transcriptional machinery and regulates target genes. Previous studies showed that TCF4 was involved in cell proliferation and apoptosis. Human haploinsufficiency of the transcription factor Tcf4 leads to a rare autism spectrum disorder called Pitt-Hopkins syndrome (PTHS), which is associated with severe language impairment and development delay.