Association of MMP 3 COL 5 A 1 and COL 1 A 1 gene polymorphisms with ACL geometric size in Chinese population

Introduction: The anterior cruciate ligament is one of the most frequently injured structures within the knee joint. Previous study reported positive relationship between small anterior cruciate ligament (ACL) and injury risk. The major structural constituents of ligaments are collagens, but no study reported the relationship between the size of ACL and the genes encoding collagens. This study was conducted to investigate whether the gene polymorphisms of MMP3, COL5A1, COL1A1 are associated with the size of anterior cruciate ligament in Chinese. Materials and methods: 106 Chinese participants without any history of previous ligament or tendon injuries have been recruited. All participants received 1.5-T magnetic resonance imaging of both knees and the length and width of the anteromedial (AM) and posterolateral (PL) bundle of ACL were measured. Meanwhile, all participants were genotyped for MMP3 variant (rs679620), COL5A1 variant (rs12722) and the COL1A1 variant (rs1107946). Results: The t-test showed longer AM bundle (39.27 ± 1.24 versus 37.16 ± 2.06 mm, P<0.001) and thicker PL bundle (3.29 ± 0.68 versus 2.76 ± 0.70 mm, P=0.007) in male. Among three genotypes of the MMP3 rs679620, the GG genotype had longest AM bundle (38.92 ± 1.96 mm, P=0.024) and widest PL bundle (3.39 ± 0.54 mm, P<0.001), while the AG had the widest AM bundle (3.10 ± 0.58 mm, P=0.002). The genotypes of COL1A1 rs1107946 were distributed by sex. Most men had a TT genotype (77%) with longer AM and PL bundle (38.67 ± 1.43 mm, 20.59 ± 1.39 mm). TT genotype had longest AM and PL bundle (38.67 ± 1.43 mm, 20.59 ± 1.39 mm), while GG genotype had shortest AM and PL bundle (37.28 ± 1.57 mm, P=0.039; 19.22 ± 1.34 mm, P=0.015, respectively). Conclusion: The geometric size of ACL was influenced by the MMP3 rs679620 and the COL1A1 rs1107946 variant.