eLife Assessment
This is an important study that identifies the developmental time window during which re-expression of TCF4 mutated in Pitt-Hopkins syndrome, can rescue phenotypic features of brain function in a TCF4 knockout mouse. The study presents compelling data using a viral transgenic intersection approach to show that TCF4 expression is required early in perinatal life. These findings have implications for the timing of possible gene therapy in people with Pitt-Hopkins-associated TCF4 mutations.