Abstract
Pathogenic variants in genes that encode epigenetic regulators are the cause for more than 100 rare neurodevelopmental syndromes also termed "chromatinopathies". DNA methylation signatures, syndrome-specific patterns of DNA methylation alterations, serve as both a research avenue for elucidating disease pathophysiology and a clinical diagnostic tool. The latter is well established, especially for the classification of variants of uncertain significance (VUS). In this perspective, we describe the seminal DNA methylation signature research in chromatinopathies; the complex relationships between genotype, phenotype and DNA methylation, and the future applications of DNA methylation signatures.