The Genetics of Being Injury-Prone

Researchers are beginning to understand how DNA makes some athletes more likely to get hurt.

Injury is a fact of life for most athletes, but some professionalsand some weekend warriors, for that matterjust seem more injury-prone than others. But what is it about their bodies that makes the bones, tendons, and ligaments so much more likely to tear or strainbad luck, or just poor preparation?

A growing body of research suggests another answer: that genetic makeup may play an important role in injury risk.

A review article recently published in the Clinical Journal of Sports Medicine emphasizes that research on the genetics of sports injuries holds great potential for injury prevention for athletes at every level. The authors, from Stanford Universitys department of developmental biology and genetics, believe that genetic testing also gives athletes valuable information that might increase their competitive edge.

Stuart Kim, one of the studys authors and a professor of genetics at Stanford, says his interest in sports injuries began almost by accident. I initially intended to study the genes associated with the large size of NFL lineman, but the athletes werent really interested in finding out the genetic reasons why they were so big, Kim says. But they were extremely interested in figuring out what injuries they were more likely to sustain.

Genetic information can be valuable for amateur athletes, tooregardless of skill level, someone about to join a recreational basketball league or a tennis club would be well-served to know if theyre at risk of blowing out an ACL or tearing an Achilles. Each year, around 2 million adults go to the emergency room for sports-related injuries, many of them acquired during pickup games or matches in recreational leagues.

Within the field of sports-injury genetics, some studies have focused on variations in the genes that control the production of collagen, the main component of tendons and ligaments. Collagen proteins also form the backbone of tissues and bones, but in some people, structural differences in these proteins may leave the bodys structures weaker or unable to repair themselves properly after injury. In a study published in the British Journal of Sports Medicine in 2009, South African researchers found that specific variations of a collagen gene named COL1A1 were under-represented in a group of recreational athletes who had suffered traumatic ACL injuries. Those who had torn their ACL were four times as likely as the uninjured study subjects to have a blood relative who had suffered the same injury, suggesting that genetics are at least partially responsible for the strength of the ligament.

The same COL1A1 gene has also been linked to other soft-tissue injuries, like Achilles-tendon ruptures and shoulder dislocations. In a review article that combined the results of multiple studies on the COL1A1 gene, published in the British Journal of Sports Medicine in 2010, researchers concluded that those with the TT genotypeone of three potential variants of the gene, found only in 5 percent of the populationare extremely unlikely to suffer a traumatic ligament or tendon injury.

However, because of the vast complexity of the human genome, its highly improbable that a single variant within a gene can determine a persons genetic risk for a given soft-tissue injury. Researchers agree its much more likely that these injuries, like complex conditions such as obesity or type 2 diabetes, are influenced by multiple genes.

The COL5A1 gene, another one associated with collagen production, has been linked to a higher risk of injury of the ACL and Achilles tendon, as well as greater susceptibility to exercise-induced muscle cramping. A 2013 study in the Clinical Journal of Sports Medicine found that specific variants of COL5A1 were strongly correlated with muscle cramping among runners in the Two Oceans Marathon in South Africa.

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The Genetics of Being Injury-Prone