Aberrant epigenetic landscape in intellectual disability.

In recent decades, epigenetics has emerged as a broad-ranging regulatory layer that modulates the whole genome and transcriptome. It largely determines the firing of transcription start sites, the splicing processes, and the binding of transcription factors, among many other processes. Its wide spectrum of action has provided us with the keys to new doors to investigate many diseases, including intellectual disability syndromes. The involvement of epigenetic factors in Rett syndrome is already well established, and its involvement in alpha-thalassemia/mental retardation-X-linked and Rubinstein-Taybi syndromes is also being elucidated. Down syndrome is not an exception, and the most recent reports suggest that epigenetic factors may play a crucial role in its etiology and also have the potential to provide new panels of biomarkers and tailored treatments.