MUC5AC and neoplasm: Among the genes shared in normal and tumor tissues, several genes involved in polymorphism, or which were reported to be related to cancer predisposition or progression were included, such as, the human leukocyte antigen (HLA) on chromosome 6, members of the mucin gene family (MUC) on chromosome 3, and the MAP2K3 and CDC27 locus, which is involved in the cell proliferation and cell cycle on chromosome 7.