MSH2 and mismatch repair cancer syndrome 1: The msh2∆ mutation present in this hybrid allows the detection of virtually all interhomolog recombination events, since most DNA heteroduplexes (hDNA) formed during recombination between polymorphic parental sequences are maintained due to MMR deficiency, whereas they would lead to gene conversions or restorations of the parental alleles in the MSH2 background (Figure 8a) (Martini et al., 2011).