RECQL4 and Rothmund-Thomson syndrome: Further to this discovery, it was established that while RECQL4 mutations are observed in ca.60% of RTS patients, a further 40% did not have variants identified in this gene, such that the disease was subdivided into RTS type 1 (no variants identified in RECQL4) and type 2 (biallelic variants in RECQL4) (Wang et al., 2003; Larizza et al., 2010; Wang and Plon, 2020).