HAS1 exhibited significant downregulation in bladder urothelial carcinoma (BLCA), breast invasive carcinoma (BRCA), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), glioblastoma multiforme (GBM), kidney chromophobe (KICH), liver hepatocellular carcinoma (LIHC), lung adenocarcinoma (LUAD), lung squamous cell carcinoma (LUSC), uterine corpus endometrial carcinoma (UCEC), brain lower grade glioma (LGG), ovarian serous cystadenocarcinoma (OV), and skin cutaneous melanoma (SKCM). The gene discussed is HAS1; the disease is ovarian serous cystadenocarcinoma.