MRE11 and ataxia-telangiectasia-like disorder: Loss of Nbs1 or Mre11 is embryonic lethal [80, 81] and mutations in NBS1 and MRE11 lead to the chromosomal instability disorders Njimegen breakage syndrome (mutation in NBS) and ataxia telangiectasia-like disorder (ATLD; mutation in Mre11).