BACKGROUND:A large number of domestic and international documents have confirmed that elevated interleukin-1β is associated with primary frozen shoulder.Interleukin-1B gene polymorphisms can affect the transcription and protein expression of interleukin 1β-related genes,resulting in altered levels of cytokines in vivo,and thus altering the incidence of primary frozen shoulder.Through the study of interleukin-1B gene polymorphism and susceptibility to primary frozen shoulder,this study aimed to explore new breakthroughs in the pathogenesis of primary frozen shoulder from the perspective of molecular biology,and to search for susceptibility genes of primary frozen shoulder. OBJECTIVE:To explore the association between linkage disequilibrium of three gene loci in interleukin-1B gene and susceptibility to primary frozen shoulder. METHODS:A case-control study was conducted.There were two groups in this study.One group consisted of 184 patients with primary frozen shoulder,while the other group included 260 healthy controls.The genotypes of interleukin-1B gene loci-511C/T(rs16944),+3954C/T(rs1143634),and-31C/T(rs1143627)were detected by polymerase chain reaction and restriction fragment length polymorphism.The correlation between the probability of linkage disequilibrium and haplotypes and the risk of primary frozen shoulder disease was compared and analyzed. RESULTS AND CONCLUSION:Unconditional Logistic regression analysis showed that the proportion of CT genotypes at rs1143634 and rs1143627 sites increased significantly in the primary frozen shoulder.Linkage disequilibrium analysis showed that rs16944,rs1143634 and rs1143627 tended to be balanced in the control group(D'value<0.1),while there was a certain degree of linkage disequilibrium at rs1143627 and rs1143634 sites in the primary frozen shoulder group(D'value=0.595).Haplotype TTT increased the risk of primary frozen shoulder by 6.66 times compared with CCT type(TTT,OR=6.66,95%CI=1.59-27.88,P=0.009 7).To conclude,there is a certain degree of linkage disequilibrium between interleukin-1B gene loci rs1143627and rs1143634 in patients with primary frozen shoulder;haplotype TTT formed by these three gene loci may increase the risk of developing primary frozen shoulder.