Tendinopathies in upper extremities (arms)

Tendons are anatomical structures located between the muscle and the bone, whose function is to transmit the force generated by the muscle to the bone, giving rise to joint movement. The influence of genetics in tendon pathologies is increasingly known, which allows a more exhaustive knowledge of the interpretation of genetic variations, not only in the causes of tendinopathies but also in other aspects such as susceptibility, prognosis and individual response to treatments.

The rotator cuff muscles are small, stabilizing muscles of the shoulder joint that allow precise and coordinated shoulder movements. They are composed of four muscles (supraspinatus, subscapularis, teres minor and infraspinatus) and their responsible tendons.

Of the four rotator cuff muscles, the most frequently injured tendon is the supraspinatus. Injury to this tendon occurs mainly due to tissue degeneration due to vascularization deficits, direct trauma or overload due to exhaustive use with different workloads.

One of the main characteristics associated with the tendon is its ability to modulate, and therefore its potential ability to recover from injury. To this end, it is important to know the intrinsic, individual, genetic, biomechanical and environmental factors that interact with each other and that make it possible to prevent and optimize recovery from tendinopathies.

Several studies have identified 3 markers associated with the risk of tendon injuries in rotator cuffs. These markers are found in COL1A1, a gene that codes for type I collagen and whose variants have been associated with tendinopathies and ligament ruptures, as well as other connective tissue pathologies (osteogenesis imperfecta and Ehlers-Danlos syndrome). We can also find the DEFB1 gene, which produces the beta-defensin 1 protein, an antimicrobial peptide expressed on epithelial surfaces and which is also implicated in other pathologies such as muscular dystrophy and cystic fibrosis. The third gene analyzed is the tenascin-C gene (TNC). Certain variants in TNC may contribute to a greater or lesser risk of injury to the tendons that attach the arm to the shoulder and that occur frequently in athletes.

Number of observed variants

13.5 million variants

Number of variants analyzed in the study

3 variants

Bibliography

Khoschnau S, Melhus H, Jacobson A, Rahme H, Bengtsson H, Ribom E, et al. Type I Collagen ?1 Sp1 Polymorphism and the Risk of Cruciate Ligament Ruptures or Shoulder Dislocations. Am J Sports Med, 2008; 36(12):2432–6.

Kluger R, Burgstaller J, Vogl C, Brem G, Skultety M, Mueller S. Candidate gene approach identifies six SNPs in tenascin-C (TNC) associated with degenerative rotator cuff tears. J Orthop Res, 2017; 35(4):894–901.

Motta G da R, Amaral MV, Rezende E, Pitta R, dos Santos Vieira TC, Duarte MEL, et al. Evidence of genetic variations associated with rotator cuff disease. J Shoulder Elb Surg, 2014; 23(2):227–35.

Vaughn NH, Stepanyan H, Gallo RA, Dhawan A. Genetic Factors in Tendon Injury: A Systematic Review of the Literature. Orthop J Sport Med, 2017; 5(8):232596711772441.

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