The higher immune score as defined by overexpression of immune signaling pathways in low PER TCGA clusters (Circadian2 and Circadian4) as compared to the high PER counterparts (Circadian1 and Circadian3) and the differential expression of PER based on tumor location raised the question of whether different cellular types within the glioma tumors differ in their expression of clock genes. The gene discussed is CLOCK; the disease is central nervous system cancer.