In humans, five members of the RecQ helicase family have been identified: RECQL1, RECQL4, RECQL5, BLM and WRN. Mutations in three are associated with syndromes that present with premature aging and cancer-predisposition: WRN in Werner’s syndrome, BLM in Bloom’s syndrome, and RECQL4 in RTS [8, 9]. Here, BLM is linked to Bloom syndrome.