IL1A and intervertebral disk degenerative disorder: They showed that the carriage of the Trp3 allele of COL9A3 in the absence of the T allele of IL-1 increased the risk of dark nucleus pulposus and joint occurrence of degenerative changes, while there was no effect of the Trp3 allele in the presence of the IL-1 T allele, suggesting that IL-1 gene polymorphism may modify the effect of the COL9A3 in IDD patients [32].