POLH（DNA polymerase eta），癌症关联基因，基因ID：5429，这个基因编码一个特殊dna聚合酶y家族的成员。它复制未受损的DNA，保真度比其他DNA定向聚合酶低。然而，它能准确复制紫外线损伤的dna；当存在胸腺嘧啶二聚体时，这种聚合酶在新合成的dna中插入互补核苷酸，从而绕过损伤并抑制紫外线诱导dna损伤的诱变效应。这种多聚酶被认为参与了免疫球蛋白类开关重组过程中的高突变。该基因突变导致xpv，一种色素性干皮病的变种。已经发现了一些编码不同亚型的转录变体。[由RefSeq提供，2014年5月]This gene encodes a member of the Y family of specialized DNA polymerases. It copies undamaged DNA with a lower fidelity than other DNA-directed polymerases. However， it accurately replicates UV-damaged DNA; when thymine dimers are present， this polymerase inserts the complementary nucleotides in the newly synthesized DNA， thereby bypassing the lesion and suppressing the mutagenic effect of UV-induced DNA damage. This polymerase is thought to be involved in hypermutation during immunoglobulin class switch recombination. Mutations in this gene result in XPV， a variant type of xeroderma pigmentosum. Several transcript variants encoding different isoforms have been found for this gen。