It is plausible that our study might also underestimate the rate of somatic alteration because we previously identified five additional mutations in the TP53 gene [6] (Langerod and coworkers, unpublished data) in the Norwegian tumor samples using a highly sensitive screening technique, namely temporal temperature gel electrophoresis (TTGE), prior to sequencing (these mutations are marked in Additional file 2). The gene discussed is TP53; the disease is neoplasm.