BLM and Bloom syndrome: Taken together, we have identified five new BLM missense mutations that exhibit defects of the Bloom syndrome associated blmASH null allele and are therefore new candidates for Bloom syndrome causing alleles, and three new BLM missense mutations that exhibit some defects (elevated interchromatid crossover recombination (SCEs), slower accumulation and markedly delayed elimination of γH2AX after genotoxin exposure, and inefficient repair of replication‐dependent DSBs), but not others (HU hypersensitivity, accumulation of quadriradial chromosomes) (Table 2).