COL1A1 and intervertebral disk degenerative disorder: To determine the expression levels of these dysregulated genes in IDD patients, we collected blood leukocyte samples from 20 healthy controls and 20 IDD patients under Pfirrmann grade IV and then measured the mRNA levels of PUMA, KLF17 (Krüppel-like factor 17), TGM2 (transglutaminase 2), COL1A1 (collagen type I alpha 1 chain), AXIN1 (axin 1), and XPO1 (exportin 1) as examples.