These include the deletion of 13q or “del(13q)” as a sole abnormality, which is considered a favorable prognostic marker; the gain of an additional copy of chromosome 12 or “trisomy 12” (+12) and a negative CLL FISH panel result (also called “normal karyotype”), which are both categorized as intermediate prognostic markers; the deletion of 11q or “del(11q)” involving the ATM Serine/Threonine Kinase (ATM) gene and flanking regions; and the deletion of 17p or “del(17p)” involving the Tumor Protein P53 (TP53) gene and flanking regions, which are both defined as unfavorable prognostic markers. The gene discussed is TP53; the disease is B-cell chronic lymphocytic leukemia.