Genetic alterations of several autosomal dominant genes associated with IDDs have been identified and numbered, with MRD1 (“mental retardation”, autosomal dominant 1) referring to mutation or disruption of the gene MBD5 and MRD2 to disruption of DOCK8. Since the abbreviation “MR” for “mental retardation” is being replaced with “ID” for intellectual disability, here we use “IDD” instead of “MRD” in this Mini Review. Here, MBD5 is linked to Intellectual disability.