Similarities and Differences in the Cohesinopathies of Roberts Syndrome and Cornelia de Lange Syndrome

Cohesins were first identified based on their role in chromosome segregation. The products of chromosome replication must be identified from S phase until anaphase onset in mitosis to ensure high fidelity chromosome segregation. Cohesin complexes tether together sister chromatids to maintain identity over time. More recently, cohesins were found to play numerous roles in transcription regulation and other forms of DNA metabolism, including the firing of clustered DNA replication forks, insulator function, and replication fork restart. Genetic mapping that revealed cohesin mutations are responsible for severe developmental defects spurred intense research regarding which role of cohesins was crucial to proper development. Cohesinopathies are a group of developmental disorders caused by disruption in cohesin function. Cornelia de Lange Syndrome (CdLS) and Roberts Syndrome (RBS) are two examples of cohesinopathies that exhibit a similar suite of phenotypes but are thought to arise through very different cellular mechanisms. This review investigates the similarities and differences between these two disorders to formulate a hypothesis unifying the relationship of these disorders as a possible continuum of manifestations caused by the same underlying mechanism.