Figure 5 showed statistically significant differences (P < 0.05) except for STAT3, LYAR, and SART1, the expression levels of PRIM1, KIF20B, and MSH2 were higher in disc degeneration subtype 1 (Cluster 1) than in subtype 2 (Cluster 2). However, the expression of RCOR2, NOTCH1, and SP1 in cluster1 was lower than that in cluster2 (up-regulated in cluster2). Finally, we used the ‘pheatmap’ package in R to generate a heatmap showing the expression differences of the nine hub genes in the two-disc degeneration subtypes (Figure 5F). The gene discussed is NOTCH1; the disease is intervertebral disk degenerative disorder.