RecQ helicases are implicated in DNA recombination and repair helicases and are critical in genome maintenance. RecQL5 is one of five known RecQ homologues in humans, and defects in three of these (BLM, WRN and RecQ4)are associated with autosomal recessive disorders that involve genomic instability and a predisposition to cancer. The exact role of ReqL5 is unclear. It has been shown in mouse embryonic stem (ES) cells that mutations in the Recql5 genes result in a significant increase in the frequency of sister chromatid exchange (SCE), whereas deleting Recql5 lead to an even higher frequency of SCE. There are three different RecQL5 isoforms - alpha, beta and gamma, produced by alternative splicing.