Molecular and Cellular Function of TCF4 in Pitt-Hopkins Syndrome

Transcription factor 4 (TCF4, also known as ITF2 or E2-2) is a type I basic helix-loop-helix (bHLH) transcription factor. Autosomal dominant mutations in TCF4 cause Pitt-Hopkins syndrome (PTHS), a rare syndromic form of autism spectrum disorder (ASD). In this review, we provide an update on the progress regarding our understanding of TCF4 function at the molecular, cellular, physiological and behavioral levels with a focus on phenotypes and therapeutic interventions. We examine upstream and downstream regulatory networks associated with TCF4 and discuss a range of in vitro and in vivo data with the aims of understanding emerging TCF4-specific mechanisms relevant for disease pathophysiology. In conclusion, we provide comments about exciting future avenues of research that may provide insights into potential new therapeutic targets for PTHS.