ARK2N and Poirier-Bienvenu neurodevelopmental syndrome: A KSSR motif (AA 147–150), located at the interface of the β-β dimer, has been shown to be required for two other CK2 substrates, the Epstein-Barr virus EBNA1 protein and C18orf25/ARKL1 (Cao et al., 2014), however no such variants have been identified in POBINDS patients.