Particularly in humans, DNA polymerase η (Polη), a Y-family DNA polymerases (1), plays an important role in preventing cell death and mutagenesis after ultraviolet (UV) light irradiation, and malfunction of Polη causes the inherited genetic disorder, xeroderma pigmentosum variant (XP-V) (2–4). Here, POLH is linked to Xeroderma pigmentosum variant.