DNAH8 and xeroderma pigmentosum: Mutations clustered around the ATPase cleft and ssDNA binding groove were categorized into two main groups: 1) mutations that weaken ssDNA binding that are primarily associated with XP, and 2) mutations that rigidify the helicase core or destabilize the RecA1–RecA2 interface—a mechanism principally operational for XP/CS mutations.