COL5A1 rs13946: What Your Genotype Means
The rs13946 variant is a genetic change located within the COL5A1 gene, which provides instructions for building type V collagen. Research suggests this variant may influence physical traits such as joint flexibility and the risk of sustaining tendon or ligament injuries.
What each genotype means
Associated with ligament injury risk
Research indicates that this genotype may be associated with an increased risk of anterior cruciate ligament (ACL) injury in certain female athletic populations. Because findings are mixed and often specific to certain sports or ancestries, this result should be viewed as exploratory rather than diagnostic.
This genotype is common in populations of European ancestry, where the C allele is frequently observed.
Variable ligament injury profile
This heterozygous genotype represents a mix of the two common alleles. Studies have not consistently linked this specific combination to a distinct clinical phenotype, and its influence on tendon or ligament health remains unclear in the current scientific literature.
This is a common genotype found in many populations, reflecting the high prevalence of both the C and T alleles.
Potential ligament injury susceptibility
Some meta-analyses and studies suggest that the T allele, particularly under a recessive model, may be associated with an increased risk of ACL injuries in specific cohorts. These associations are limited and context-dependent, meaning they do not predict individual injury outcomes.
This genotype is found in a significant portion of the population, consistent with the frequency of the T allele in European cohorts.
Understanding the rs13946 Variant
The rs13946 variant is a single nucleotide polymorphism (SNP) located in the 3'-untranslated region (3'-UTR) of the COL5A1 gene. Unlike variants that change the amino acid sequence of a protein, this SNP is synonymous, meaning it does not alter the protein's structure directly. Instead, researchers believe that variants in the 3'-UTR may influence the stability of the mRNA molecule or how efficiently the gene is expressed. Because this region is involved in regulating gene activity, changes here can potentially affect the amount of collagen produced in tissues. Located on chromosome 9, the COL5A1 gene is a critical player in the structural integrity of the body's connective tissues. Scientists study this specific location to understand why individuals may have different baseline levels of flexibility or varying susceptibility to soft tissue injuries during physical activity.
The Role of COL5A1 in Connective Tissue
The COL5A1 gene is responsible for producing the pro-alpha1(V) chain, a vital component of type V collagen. Collagen is the most abundant protein in the human body, acting as the 'glue' that holds tissues together. Type V collagen is particularly important for the formation of fibrils in tendons, ligaments, skin, and muscles. By providing structural support, these collagen fibers ensure that tissues can withstand mechanical stress and maintain their elasticity. When the expression of this gene is altered, it can lead to differences in the mechanical properties of these tissues. While severe mutations in COL5A1 are known to cause conditions like Ehlers-Danlos syndrome, which involves joint hypermobility, common variants like rs13946 are thought to have much more subtle effects on the normal range of motion and injury resilience in the general population.
Research on Fitness and Injury Risk
Scientific interest in rs13946 stems from its potential link to athletic performance and injury susceptibility. Several studies have investigated whether this variant correlates with sit-and-reach flexibility, running economy, and the risk of anterior cruciate ligament (ACL) or Achilles tendon injuries. The evidence, however, is mixed and often context-dependent. Some research suggests that certain genotypes may be protective against ligament tears, while others might be associated with an increased risk of tendon pathology. These associations are frequently observed in specific athletic cohorts, such as professional soccer players or runners, and results often vary by ancestry and gender. Because these studies often involve relatively small sample sizes and complex environmental factors, the evidence remains limited. It is important to view these findings as statistical associations within populations rather than definitive predictors of an individual's physical future or injury risk.
Interpreting Your Genetic Information
If you have access to your genetic data regarding rs13946, it is essential to understand that this information is not a medical diagnosis. Genetic variants are only one of many factors that contribute to your physical health and injury risk. Environmental influences—such as training intensity, nutrition, recovery habits, and biomechanics—play a significantly larger role in determining your athletic performance and injury outcomes. You cannot use this information to predict your future health or to create a personalized medical plan. If you are concerned about joint health, flexibility, or injury prevention, the most effective approach is to consult with a physical therapist, sports medicine physician, or a qualified athletic trainer. They can provide evidence-based guidance tailored to your specific physical needs and goals, regardless of your genetic profile.
How common is this variant?
The minor allele (A) frequency for rs13946 is approximately 0.40 in European cohorts, though frequencies can vary significantly across different global populations.
Frequently asked questions
Does the rs13946 variant mean I will get an injury?
No. Genetic variants like rs13946 only provide a small statistical association with injury risk. Most injuries are caused by environmental factors like training load, technique, and recovery.
Can I change my risk based on my COL5A1 genotype?
You cannot change your genotype, but you can manage your injury risk through proper training, strength conditioning, and adequate recovery. Consult a sports medicine professional for personalized advice.
Is rs13946 the same as the BstUI polymorphism?
No, they are different markers. While both are located in the COL5A1 gene and are often studied together, rs13946 is a distinct variant from the BstUI (rs12722) polymorphism.
Where can I find more information on COL5A1?
You can search the NCBI Gene database or MedlinePlus Genetics for comprehensive information on the function of the COL5A1 gene and its role in human health.
Sources & further reading
Educational information only, last refreshed 10/15/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Variant in the collagen type V alpha 1 chain gene associated with range of motion, muscle-tendon stiffness, and soft-tissue injury susceptibility.
Common regulatory intronic variant in COL5A1 significantly associated with central corneal thickness variation and susceptibility to keratoconus.
COL5A1 locus variant robustly associated across multiple genome-wide scans with decreased central corneal thickness and corneal biomechanical risk.
Polymorphism located within the 3' untranslated region of COL5A1 associated with musculoskeletal soft tissue properties, Achilles tendinopathy, and cruciate ligament injury risk.
This variant is associated with joint hypermobility and susceptibility to hypermobile Ehlers-Danlos Syndrome.
This variant in the collagen type V alpha 1 chain gene is associated with structural skin integrity and connective tissue properties.