The older patients with tumors expressing hormonal receptors and a high level of mucin 1 tend to group into clusters I to III (or A and B), while the carcinomas of younger patients exhibiting triple negative (that is, ER, progesterone receptor, HER2/neu) phenotype, high nuclear grade and basal cytokeratin 5/6 and/or cytokeratin 14 locate more often to cluster IV and especially cluster V (or C). The gene discussed is KRT5; the disease is carcinoma.