GDF5 and intervertebral disk degenerative disorder: The expression levels of genes that have been confirmed to be associated with the development of IDD were assessed in different clusters, of which APOE, ATXN7, LMNA, GDF5, and HGD were overexpressed in MAPK cluster A and gene cluster A, whereas SNRNP200, OFD1, and NT5E were downregulated in MAPK cluster A and gene cluster A (Figure 6C).