HYAL4 and central nervous system cancer: In the Chinese Glioma Genome Atlas (CGGA) database, survival filtration analysis was performed to find the DEGs in mRNA-array_301, mRNA-seq_325 and mRNA-seq_693; next, intersection analysis was used to identify overlapping genes between DEGs screened in mRNA-array_301, mRNA-seq_325 and mRNA-seq_693 and HAase genes (HYAL1, HYAL2, HYAL3, HYAL4, HYALP1, SPAM1), and again, HYAL2 was the only overlapping gene (Supplementary Fig. 1B).