What you carry at this position in your DNA and what research says about it.
Red Blood Cell Traits: 10/10 evidence, 30 publications.
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Sample genotype (not yours): C/C
Typical Blood Cell Characteristics
This genotype is associated with a typical red blood cell count and standard red blood cell size. It represents the most common genetic profile globally.
What this genotype means: Standard red blood cell size; Typical baseline platelet count.
Sample genotype (not yours): C/T
Intermediate Blood Cell Characteristics
This genotype is associated with slightly higher red blood cell counts and slightly smaller red blood cell sizes. It represents a balanced, intermediate physiological profile.
What this genotype means: Slightly higher red blood cell count; Slightly smaller red blood cell size.
Sample genotype (not yours): T/T
Higher Red Blood Cell Count and Smaller Cell Size
This genotype is associated with a higher number of red blood cells that are slightly smaller in size. It represents a normal physiological variation with no negative health impacts.
What this genotype means: Higher red blood cell count; Smaller average red blood cell size.
Gene function and biological role
Gene Function: TRIM58 encodes tripartite motif containing 58, an E3 ubiquitin-protein ligase that plays a critical role in the development of red blood cells [1]. It is highly expressed in late-stage erythroid precursor cells, where it targets specific proteins like dynein for degradation to facilitate cell maturation [1]. This degradation process is essential for the normal structural remodeling and nuclear extrusion of developing red blood cells [1]. Genetic variations in this gene can alter its ligase activity, thereby influencing various hematological parameters [2].
Variant Impact: The rs3811444 variant is a missense mutation in the TRIM58 gene that results in an amino acid substitution from threonine to methionine at position 374 (p.Thr374Met). This structural change occurs within the functional domain of the TRIM58 protein, potentially altering its interaction with target proteins during red blood cell development. Studies have shown that this specific variant is strongly associated with variations in red blood cell size, hemoglobin concentration, and overall red blood cell count [1] [2]. It represents one of the most prominent genetic modifiers of baseline blood cell characteristics in diverse populations [2].
Key Insight: This variant acts as a natural fine-tuner of your blood composition, subtly shifting the balance between the size and the total number of your red blood cells.
Location: TRIM58. Chromosome 1 · 1q44 · 247.9 Mb
Estimated prevalence by population
Global 55.1%; European 43.0%; African 83.7%; East Asian 59.1%; South Asian 45.3%; Americas 47.0%; Ashkenazi 40.3%; Finnish 42.3%; Middle Eastern 52.5%; Amish 32.9%.
Estimated CC genotype frequency.
Global 36.5%; European 45.1%; African 15.6%; East Asian 35.5%; South Asian 44.0%; Americas 43.1%; Ashkenazi 46.4%; Finnish 45.5%; Middle Eastern 39.9%; Amish 48.9%.
Estimated CT genotype frequency.
Global 8.4%; European 11.8%; African 0.7%; East Asian 5.3%; South Asian 10.7%; Americas 9.9%; Ashkenazi 13.4%; Finnish 12.2%; Middle Eastern 7.6%; Amish 18.2%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Blood Cell & Iron Traits
Red Blood Cell Count. Evidence: 10/10. Source: PMID 32888494. Typical.
Red Blood Cell Size. Evidence: 10/10. Source: PMID 27863252. Larger.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 32888494. Typical.
Red Cell Distribution Width. Evidence: 10/10. Source: PMID 28957414. Higher Variation.
Platelet Count. Evidence: 10/10. Source: PMID 22139419. Higher.
White Blood Cell Count. Evidence: 10/10. Source: PMID 27863252. Typical.
Showing effects for C/T genotype
Red Blood Cell Count. Evidence: 10/10. Source: PMID 32888494. Slightly Higher.
Red Blood Cell Size. Evidence: 10/10. Source: PMID 27863252. Slightly Smaller.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 32888494. Slightly Higher.
Red Cell Distribution Width. Evidence: 10/10. Source: PMID 28957414. Slightly Lower.
Platelet Count. Evidence: 10/10. Source: PMID 22139419. Slightly Lower.
White Blood Cell Count. Evidence: 10/10. Source: PMID 27863252. Slightly Higher.
Showing effects for T/T genotype
Red Blood Cell Count. Evidence: 10/10. Source: PMID 32888494. Higher.
Red Blood Cell Size. Evidence: 10/10. Source: PMID 27863252. Smaller.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 32888494. Higher.
Red Cell Distribution Width. Evidence: 10/10. Source: PMID 28957414. Lower Variation.
Platelet Count. Evidence: 10/10. Source: PMID 22139419. Lower.
White Blood Cell Count. Evidence: 10/10. Source: PMID 27863252. Higher.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Carrying two copies of the C allele is associated with a baseline physiological profile for red blood cells and platelets. Individuals with this genotype tend to have a typical red blood cell count and standard hemoglobin levels [1]. However, their red blood cells are slightly larger on average, as indicated by a higher mean corpuscular volume (MCV) compared to T allele carriers [2]. There is also a slightly higher red cell distribution width (RDW), which measures the variation in red blood cell size [3]. Platelet counts also tend to be slightly higher in this group [4]. These variations represent normal physiological diversity rather than any clinical disorder or disease risk.
Standard red blood cell size; Typical baseline platelet count.
Sample genotype: CT (Heterozygous)
Carrying one copy of the T allele and one copy of the C allele results in an intermediate blood cell profile. This heterozygous state is associated with a slight increase in red blood cell count and hemoglobin levels compared to the C/C genotype [1]. Conversely, the average size of these red blood cells (mean corpuscular volume) is slightly smaller [2]. There is also a minor reduction in red cell distribution width, meaning the red blood cells are more uniform in size [3]. Platelet counts are also slightly lower, while white blood cell counts show a very minor increase [4]. These subtle shifts are completely benign and fall well within the normal range of human variation.
Slightly higher red blood cell count; Slightly smaller red blood cell size.
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele is associated with a distinct physiological profile characterized by more numerous but smaller red blood cells. Individuals with this genotype typically exhibit higher red blood cell counts and elevated hemoglobin levels [1]. To balance this, their red blood cells are slightly smaller on average, as shown by a lower mean corpuscular volume (MCV) [2]. They also have a lower red cell distribution width (RDW), indicating highly uniform red blood cell sizes [3]. Additionally, this genotype is linked to slightly lower platelet counts and minor increases in white blood cell counts [4]. These characteristics are normal genetic variations and do not indicate anemia or any other hematological condition.
Higher red blood cell count; Smaller average red blood cell size.
Variants with shared genetic architecture
rs1339847 · TRIM58 Gene · Chr 1 · Blood Cell Characteristics
rs1434282 · LINC01221 Gene · Chr 1 · Blood Cell Characteristics
rs6592965 · IKZF1 Gene · Chr 7 · Red Blood Cell Size
The Polygenic and Monogenic Basis of Blood Traits and Diseases.
The Allelic Landscape of Human Blood Cell Trait Variation and Links to Common Complex Disease.
Red blood cell distribution width: Genetic evidence for aging pathways in 116,666 volunteers.
New gene functions in megakaryopoiesis and platelet formation.
Content updated August 2026.
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