Gene variants regarding ligaments, joints and bone injuries
One of the main threats of competitive sports is painful injuries. Although the abnormal proliferation, degeneration, collagen fibres tear/rupture and the increase of matrix stock of the tendon cells in case of tendinopathy have already been observed. But the etiopathogenesis of tendinopathy or its molecular changes are still waiting for further research. Individuals’ gene background together with several inner or outer factors can increase the likelihood of tendinopathy. The role of genes in tendon injuries are proved by the fact that in the Hungarian and Finnish population there was a close relationship between ABO and 0 blood types and Achilles tendon rupture or the frequency of chronic Achilles tendinopathy. These examinations revealed the relationship between ABO at the end of the arm of chromosome 9 with tendinopathy of closely related genes. The gene encoding ABO blood type contains such transfer proteins which determine the structure of the antigens of glycoprotein of RBC as well as the structure of proteins found in the extra-cellular matrix of ligament. This relationship cannot be justified, for example, in case of Scots in relation to ABO blood type and Achilles tendon rupture. It raises our attention to the dispersion specificity of ABO groups in the genetically segregated population in different geographical areas.
Genetic factors have crucial roles in the tendinopathy of rotator cuff tendons. The polimorphism of collagen-5 alpha 1 (COL5A1) and the tenascin genes can be associated with individuals’ Achilles tendinopathy who do physical activities. COL5A1 genes play important roles in the pathogenesis of Achilles tendinopathy. It was observed that South Africans having gene allele 2 the emergence of tendinopathy had small probability. Within normal circumstances the COL1A1 and COL3A1 which encode I-st and III-rd types of collagens develop in varied amount in tendon. At the same time significant expression can be detected in both genes in case of tendinopathy. The polimorphism of GT dinucleotides replication/repeat in TCN can be related to Achilles tendinopathy. Alleles containing 12 and 14 GT ‘repeat’ were significantly present in case of tendinopathy whereas alleles containing 13 and 17 GT dinucleotides emerged in the asymptomatic control group. The biological explanation of the role of TNC in Achilles tendon aetiology is the changed TNC synthesis due to the over-sized mechanical impact. It may affect cell-matrix interaction control in the tendon generating apoptotic changes in tendocyte.
Besides these genes the polimorphism of matrix-metalloproteinase-3 (MMP3) 5A/6A controlling the homeostasis of extra-cellular matrix can be related to the emergence of tendinopathy. There are more risk factors if the gene variant of MMP3 associates with the polimorphism of COL5A1.
Athletes’ joints are vulnerable and they are exposed to frequent injuries. Genetic factors also conspire in injuries. There is family predisposition in the background of the instability of the shoulders and knee anterior cruciate ligament strain and tear. These injuries can also be caused by the polymorphism of COL1A1 gene. Although researches are still in early stage it is presumed that genes have role in tendinopathy.
Figure 3. Gene variants regarding risks of tendinopathy.
Few studies deal with gene variants associated with high risks and predisposition of bone injuries. The functional gene variants of D vitamin receptors (VDR) in females’ menopause should also be mentioned. These examinations focus on the mineral content of bones as well as their density.
Figure 4. Osteoporosis- related gene variants