What you carry at this position in your DNA and what research says about it.
Iron Levels: 9/10 evidence, 22 publications.
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Sample genotype (not yours): C/C
Increased Risk of Lower Iron Levels
Carrying two copies of the C allele is associated with reduced iron absorption and lower circulating iron levels.
What this genotype means: Lower circulating iron levels; Slightly lower hemoglobin; Higher risk of iron deficiency.
Sample genotype (not yours): A/A
Efficient Iron Regulation and Higher Iron Levels
Carrying two copies of the A allele is linked to highly efficient iron absorption and robust circulating iron levels.
What this genotype means: Optimal iron absorption; Higher baseline hemoglobin; Lower risk of iron deficiency.
Sample genotype (not yours): C/A
Typical Iron Levels and Regulation
Carrying one copy of each allele results in intermediate, typical iron regulation and blood cell characteristics.
What this genotype means: Typical iron absorption; Standard red blood cell characteristics; Balanced iron regulation.
Gene function and biological role
Gene Function: The TFR2 gene encodes transferrin receptor 2, a protein primarily expressed in the liver that plays a critical role in systemic iron homeostasis [1]. Unlike its ubiquitous relative TFR1, TFR2 acts as a key component of the body's iron-sensing machinery [1]. It partners with other proteins to detect circulating iron levels and signal the production of hepcidin, the master hormone regulating iron absorption and storage [1]. Genetic variations in TFR2 can alter this sensing mechanism, leading to downstream changes in how much iron is absorbed from the diet and delivered to tissues [2]. Underperforming variants in this gene are classically linked to altered red blood cell characteristics and iron status [2].
Variant Impact: The rs7385804 variant is an intronic change located within a regulatory region of the TFR2 gene [1]. This genetic marker influences the expression levels of TFR2 mRNA in liver tissue, directly impacting the abundance of the receptor [1]. By modulating TFR2 expression, the variant alters the sensitivity of the body's iron-sensing pathway and subsequent hepcidin regulation [1]. The major A allele is consistently associated with higher serum iron, increased transferrin saturation, and elevated hemoglobin levels across diverse populations [3]. Conversely, the minor C allele correlates with reduced iron levels and compensatory changes in red blood cell size and count [3].
Key Insight: While this variant significantly influences physiological iron levels and red blood cell traits, it does not independently dictate the risk of severe clinical iron disorders like iron-deficiency anemia.
Location: TFR2. Chromosome 7 · 7q22.1 · 100.6 Mb
Estimated prevalence by population
Global 12.5%; European 14.3%; African 10.2%; East Asian 4.7%; South Asian 13.5%; Americas 7.4%; Ashkenazi 9.1%; Finnish 21.5%; Middle Eastern 6.4%; Amish 23.9%.
Estimated CC genotype frequency.
Global 44.9%; European 47.1%; African 43.5%; East Asian 34.1%; South Asian 46.5%; Americas 39.6%; Ashkenazi 42.2%; Finnish 49.7%; Middle Eastern 37.8%; Amish 50.0%.
Estimated CA genotype frequency.
Global 42.6%; European 38.6%; African 46.2%; East Asian 61.2%; South Asian 40.0%; Americas 53.1%; Ashkenazi 48.7%; Finnish 28.7%; Middle Eastern 55.7%; Amish 26.1%.
Estimated AA genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Blood Cell & Iron Traits
Iron Levels. Evidence: 9/10. Source: PMID 21208937. Lower Iron Levels.
Transferrin Saturation. Evidence: 9/10. Source: PMID 25352340. Lower Saturation.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 37596262. Lower Hemoglobin.
Red Blood Cell Count. Evidence: 10/10. Source: PMID 19820697. Higher Cell Count.
Showing effects for A/A genotype
Iron Levels. Evidence: 9/10. Source: PMID 21208937. Higher Iron Levels.
Transferrin Saturation. Evidence: 9/10. Source: PMID 25352340. Higher Saturation.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 37596262. Higher Hemoglobin.
Red Blood Cell Count. Evidence: 10/10. Source: PMID 19820697. Lower Cell Count.
Showing effects for C/A genotype
Iron Levels. Evidence: 9/10. Source: PMID 21208937. Typical Iron Levels.
Transferrin Saturation. Evidence: 9/10. Source: PMID 25352340. Typical Saturation.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 37596262. Typical Hemoglobin.
Red Blood Cell Count. Evidence: 10/10. Source: PMID 19820697. Typical Cell Count.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
This genotype is linked to lower serum iron levels and reduced transferrin saturation, which measures the amount of iron bound to transport proteins in the blood [1]. Because iron is a vital component of hemoglobin, individuals with this genotype also tend to have lower overall hemoglobin levels and smaller red blood cells [2]. To compensate for the smaller cell size, the body often produces a higher total number of red blood cells [2]. While these physiological differences are generally subtle, they can increase susceptibility to iron deficiency under conditions of low dietary intake or increased iron demand [1]. Maintaining adequate dietary iron intake is particularly relevant for individuals with this genetic profile.
Lower circulating iron levels; Slightly lower hemoglobin; Higher risk of iron deficiency.
Sample genotype: AA (Homozygous)
This genotype is associated with the highest average serum iron levels and transferrin saturation within the normal physiological spectrum [1]. The presence of two A alleles supports optimal TFR2 expression and efficient iron-sensing, which helps maintain robust iron delivery to tissues [1]. Consequently, individuals with this profile tend to have higher hemoglobin levels and larger, well-oxygenated red blood cells [2]. This genetic makeup provides natural protection against iron deficiency and microcytic anemia under standard conditions [2]. While some studies explore links to iron overload, the physiological effect of this common variant is generally healthy and adaptive.
Optimal iron absorption; Higher baseline hemoglobin; Lower risk of iron deficiency.
Sample genotype: CA (Heterozygous)
This heterozygous genotype represents a balanced genetic influence on systemic iron regulation [1]. Individuals with one C allele and one A allele typically exhibit intermediate serum iron levels and transferrin saturation compared to the homozygous groups [1]. Red blood cell markers, including mean corpuscular volume and hemoglobin concentration, generally fall within the standard physiological range [2]. The body's iron-sensing machinery in the liver operates with typical efficiency, maintaining stable hepcidin signaling under normal dietary conditions [1]. This genotype does not significantly elevate the risk for either iron deficiency or iron overload on its own.
Typical iron absorption; Standard red blood cell characteristics; Balanced iron regulation.
Variants with shared genetic architecture
rs2075672 · TFR2 Gene · Chr 7 · Iron and Blood Health
rs4820268 · TMPRSS6 Gene · Chr 22 · Iron and Hemoglobin Levels
rs2413450 · TMPRSS6 Gene · Chr 22 · Red Blood Cell Health
Novel loci affecting iron homeostasis and their effects in individuals at risk for hemochromatosis.
Content updated August 2026.
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