CSNK2A1 and Intellectual disability: For a long time, no pathogenic mutation of any of the CK2 subunit genes was known, until 2016, when Okur and coworkers analyzed 4102 intellectual disability/developmental delay cases by a whole-exome sequencing (WES) approach, and identified five patients from independent families with de novo missense and canonical splice site mutations in CSNK2A1, encoding the CK2α subunit.238 The patients shared overlapping neurodevelopmental disorders and dysmorphic features, a pathological condition that was hence defined as OCNDS (OMIM number 617062).