,81 The MRN complex, consisting of MRE11 (meiotic recombination 11), RAD50 (DNA repair protein RAD50) and NBS1 (Nijmegen breakage syndrome 1), is involved in DNA damage sensing and was found to be expressed at substantially lower levels in cortical neurons of Alzheimer’s disease brain samples compared to control samples.82 The gene discussed is RAD50; the disease is Alzheimer disease.