Pitt Hopkins syndrome (PTHS) is a rare neurodevelopmental disorder characterized by a characteristic facial appearance, poor muscle tone and coordination, unusual breathing patterns, delayed development, and a profound language impairment. The cause is haploinsufficiency of the gene for transcription factor 4 (Tcf4), a gene that has also been associated with schizophrenia. To better understand how a mutation in Tcf4 could lead to the array of symptoms associated with PTHS, Vanderbilt Basic Sciences investigator David Sweatt and his laboratory created a mouse model [Tcf4(+/-)] that bears a mutation of the Tcf4 gene structurally similar to those observed in human PTHS patients. The researchers verified that many of the developmental and behavioral abnormalities exhibited by Tcf4(+/-) mice were consistent with symptoms of PTHS. They then carried out RNA-seq and genome-wide methylation studies to investigate how the Tcf4(+/-) mutation affects gene expression in the hippocampus of affected mice. The results revealed both up- and down-regulation of key biochemical pathways associated with neuronal plasticity, learning, and memory. Of particular interest was the finding that the gene for histone deacetylase 2 (Hdac2) was markedly upregulated in Tcf4(+/-) mice. Histone deacetylase 2 removes acetyl groups from the lysine residues of histones, an important step in histone-mediated regulation of gene transcription. Consistent with this observation, the researchers found that treating Tcf4(+/-) mice with a nonselective HDAC inhibitor or with an Hdac2-selective antisense oligonucleotide resulted in a striking improvement in many of the Tcf4(+/-) mutation-related disabilities. The results provide a wealth of new information concerning the genetic and epigenetic regulation of learning and memory while also suggesting an exciting new treatment possibility for PTHS patients. The work is published in the journal Cell Reports [A. J. Kennedy, et al. (2016), Cell Rep., 16, 2666].