In this paper, I have focused on the structures of WRN and BLM, but it should be mentioned that other important RecQ structures that could not be discussed here are also available, including those of Escherichia coli RecQ (Bernstein et al., 2003; Bernstein and Keck, 2005), Deinococcus radiodurans RecQ (Killoran and Keck, 2008; Liu et al., 2013) and human RECQ1 (a protein that is not associated with genetic disease; Pike et al., 2009). The gene discussed is BLM; the disease is hereditary disease.