ATP6V1B2 and deafness-onychodystrophy syndrome: In particular, mutations in ATP6V1A, encoding V1A subunit, can promote developmental and epileptic encephalopathy (DEE) and its downregulation was associated with late-onset Alzheimer’s disease (AD), while mutations in ATP6V1B2, encoding the V1B subunit, mediate DEE, deafness, onychodystrophy, osteodystrophy, intellectual disability, and seizure (DOORS) syndrome, and Zimmermann Laband Syndrome (ZLS) (Figure 1).