A total of 20 genes are involved in these intra-category multimorbid relationships and are mainly related to the human leukocyte antigen (HLA) complex (such as HLA-DQA1 and HLA-DRB1), histone clusters (such as HIST1H1B and HIST1H2AJ), and tumors (such as TERT and NOTCH4 for prostate cancer) [49, 50]. This evidence concerns the gene HLA-DRB1 and prostate cancer.