The KDM3B (JMJD1B), REEP2, EGR1 and CTNNA1 genes lie within the MDS 5q31.2 CDR1 microdeletion region that is linked to the aggressive form of MDS and acute myeloid leukaemia [35,58–60], and this region also constitutes a 2R-WGD paralogon (figure 4). The gene discussed is KDM3B; the disease is myelodysplastic syndrome.