TMPRSS6 rs855791: What Your Genotype Means for Iron Status
The rs855791 variant is a well-studied single nucleotide polymorphism located within the TMPRSS6 gene. It is widely recognized for its statistical association with variations in iron status, hemoglobin levels, and the risk of iron deficiency anemia across diverse populations.
What each genotype means
Standard iron regulation
This genotype is associated with typical TMPRSS6 enzyme activity, which helps regulate hepcidin levels and iron absorption. Research suggests this version of the gene may be associated with higher baseline iron and hemoglobin levels compared to those carrying the T allele.
This is a common genotype, though its prevalence varies significantly by ancestry, being more frequent in populations of African descent compared to European or East Asian populations.
Intermediate iron status
Carrying one copy of the T allele is associated with a slight modulation of hepcidin levels, which can influence how your body absorbs and utilizes iron. Some studies have observed a modest decrease in average hemoglobin levels in individuals with this genotype compared to those with the CC genotype.
This heterozygous genotype is found frequently across many global populations, reflecting the common nature of the T allele in many regions.
Altered iron homeostasis
This genotype results in a V736A amino acid substitution in the TMPRSS6 protein, which has been shown to influence hepcidin transcription and iron absorption. Research indicates that individuals with this genotype may have a higher risk for iron deficiency or lower average hemoglobin levels, though this can be influenced by diet and other environmental factors.
This genotype is common in many populations, with frequencies reaching approximately 0.5 in European and 0.6 in Japanese cohorts, while being less common in African populations.
Understanding the rs855791 Variant
The rs855791 variant is a specific change in the DNA sequence of the TMPRSS6 gene, located on chromosome 22. In genetic terms, this variant involves a substitution where a cytosine (C) is replaced by a thymine (T). This specific change is often referred to in scientific literature as V736A, indicating a non-synonymous amino acid substitution in the resulting protein. Because this change occurs within the coding region of the gene, it can alter the structure or function of the protein it encodes. Researchers track this variant because it serves as a reliable marker for studying how genetic differences influence the body's ability to regulate iron. It is one of the most frequently analyzed SNPs in studies concerning hematological traits and iron homeostasis.
The Role of the TMPRSS6 Gene
The TMPRSS6 gene provides instructions for making a protein called matriptase-2. This protein acts as a critical sensor and regulator of iron levels in the body. Matriptase-2 functions primarily in the liver, where it helps control the production of hepcidin, a hormone that acts as the master regulator of iron absorption. When iron levels are sufficient, matriptase-2 suppresses hepcidin production, allowing the body to absorb more iron from the diet. If the TMPRSS6 gene contains variants that affect the efficiency of the matriptase-2 protein, it can lead to an imbalance in hepcidin levels. This, in turn, can inhibit the body's ability to absorb iron effectively, potentially leading to lower serum iron levels and a higher susceptibility to iron deficiency anemia.
Research Associations and Evidence
The association between rs855791 and iron status is supported by a significant body of research, including genome-wide association studies (GWAS). Multiple studies have linked the T-allele of this variant to lower hemoglobin levels and an increased risk of iron deficiency anemia. While the evidence is considered moderate to strong in many populations, it is important to note that findings can vary. Some studies have observed clear correlations between the variant and blood parameters, while others have reported mixed results or a lack of association in specific cohorts. This variability suggests that while rs855791 is a significant factor, iron status is a complex trait influenced by a combination of genetic, environmental, and dietary factors. Consequently, the variant should be viewed as one piece of a much larger biological puzzle.
What This Information Means for You
Knowing your genotype for rs855791 provides insight into your genetic predisposition regarding iron regulation, but it is not a diagnostic tool. Having a specific genotype does not guarantee that you will develop iron deficiency, nor does it mean you are immune to it. Iron levels are heavily influenced by lifestyle, diet, and other health conditions. If you are concerned about your iron levels or have symptoms such as fatigue or weakness, you should consult a healthcare professional for appropriate blood testing. Never use genetic information to make decisions about iron supplementation or medication without clinical guidance, as excessive iron intake can be harmful. Always discuss your health concerns and any potential dietary or medical changes with your doctor or a registered dietitian.
How common is this variant?
The rs855791 variant is common globally, with the T-allele frequency varying significantly by ancestry, ranging from approximately 0.10 in some African populations to nearly 0.50 in certain Asian and European cohorts.
Frequently asked questions
Is rs855791 a cause of anemia?
The rs855791 variant is a genetic marker associated with an increased risk of iron deficiency anemia, but it is not a direct cause. Anemia is a complex condition influenced by many factors, including diet, blood loss, and other underlying health issues.
Should I take iron supplements if I have the TT genotype?
You should never start iron supplementation based solely on your genotype. Iron overload can be dangerous, so you must consult a healthcare provider to perform blood tests and determine if you actually have an iron deficiency before considering any treatment.
How does TMPRSS6 affect my health?
The TMPRSS6 gene produces a protein that regulates hepcidin, which controls how much iron your body absorbs. Variants in this gene can make this regulation less efficient, potentially affecting your iron stores and hemoglobin levels.
Is this variant the same as having a disease?
No, having a specific genotype for rs855791 is not a disease. It is a common genetic variation that may influence your body's iron metabolism, but it does not mean you have a clinical condition.
Sources & further reading
Educational information only, last refreshed 10/8/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Modulates matriptase-2 regulation of hepcidin expression, influencing systemic iron status and individual susceptibility to dietary iron deficiency.
Variant associated with iron homeostasis, transferrin saturation, and risk of iron deficiency anemia.