RAD50 and Nijmegen breakage syndrome: When mutated, diseases such as Nijmegen breakage syndrome (NBS) and the hereditary cancer syndrome variant Li-Fraumeni (CHK2) will be developed (Matsuura et al., 1998; Varon et al., 1998; Carney et al., 1998; Featherstone & Jackson, 1998; Bell et al., 1999) suggesting the importance of these conserved residues within Rad50 for DNA repair and maintenance.