BLM can displace the invading strand from the D-loop and thus can disrupt the RAD51–ssDNA filaments, which explains why BLM has also been termed an “anti-recombination” protein, which is a feature observed in Bloom syndrome (BS) patient cells (van Brabant et al., 2000; Wu et al., 2001; Bachrati et al., 2006; Bugreev et al., 2007). Here, BLM is linked to Bloom syndrome.