ATP6V1B2 and Nail dystrophy: Haploinsufficiency of the ATP6V1B2, a subunit of V‐ATPases, underlies genetic disorders including Dominant deafness‐onychodystrophy (DDOD), deafness, onychodystrophy, osteodystrophy, mental retardation and seizures (DOORS), and Zimmermann‐Laband syndromes, all characterized by congenital hearing loss and onychodystrophy.