What you carry at this position in your DNA and what research says about it.
Cardiovascular Risk: 4/10 evidence, 22 publications.
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Sample genotype (not yours): C/C
Typical Platelet Size and Lower Cardiovascular Risk
Two copies of the C allele promote normal regulation of platelet size and activity. This genotype is associated with a lower risk of unwanted blood clots and adverse cardiac events.
What this genotype means: Typical platelet size; Lower risk of clotting complications; Standard platelet counts.
Sample genotype (not yours): C/G
Slightly Larger Platelets and Elevated Cardiovascular Risk
Carrying one copy of the G allele leads to slightly larger, more active platelets. This intermediate profile is linked to a moderately higher risk of cardiovascular events.
What this genotype means: Slightly larger platelets; Moderately increased clotting risk; Slightly lower overall platelet count.
Sample genotype (not yours): G/G
Larger Platelets and Highest Cardiovascular Risk
Two copies of the G allele result in significantly larger, highly reactive platelets. This genotype is associated with the highest risk of adverse cardiovascular events.
What this genotype means: Significantly larger platelets; Highest risk of blood clots; Lower baseline platelet count.
Gene function and biological role
Gene Function: The PIK3CG gene encodes a crucial signaling enzyme known as phosphoinositide 3-kinase gamma, which is highly active in blood platelets and immune cells. This enzyme plays a central role in directing how platelets respond to vascular injury and inflammatory signals. When PIK3CG is highly expressed, it promotes platelet activation and accelerates the formation of blood clots. Proper regulation of this gene is essential to maintain a balance between preventing bleeding and avoiding dangerous arterial blockages.
Variant Impact: The rs342293 variant is a non-coding genetic change located in a regulatory region on chromosome 7q22.3 that controls the PIK3CG gene. The major C allele serves as a strong binding site for the transcription factor EVI1, which acts as a repressor to keep PIK3CG expression at a normal, moderate level [1]. When the minor G allele is present, it disrupts this binding site, preventing the repressor from attaching and resulting in significantly increased PIK3CG expression [1]. This elevated expression alters megakaryocyte development, leading to the production of larger, more reactive platelets [2].
Key Insight: Larger platelets are biologically more active and prone to clotting, meaning that having a slightly lower overall platelet count can actually coincide with a higher risk of cardiovascular events.
Location: PIK3CG. Chromosome 7 · 7q22.3 · 106.7 Mb
Estimated prevalence by population
Global 34.4%; European 29.6%; African 38.4%; East Asian 59.2%; South Asian 39.4%; Americas 39.7%; Ashkenazi 25.1%; Finnish 27.5%; Middle Eastern 52.5%; Amish 44.9%.
Estimated CC genotype frequency.
Global 48.0%; European 49.6%; African 47.1%; East Asian 35.5%; South Asian 46.7%; Americas 46.6%; Ashkenazi 50.0%; Finnish 49.9%; Middle Eastern 39.9%; Amish 44.2%.
Estimated CG genotype frequency.
Global 17.7%; European 20.8%; African 14.4%; East Asian 5.3%; South Asian 13.8%; Americas 13.7%; Ashkenazi 24.9%; Finnish 22.6%; Middle Eastern 7.6%; Amish 10.9%.
Estimated GG genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Heart Disease
Cardiovascular Risk. Evidence: 4/10. Source: PMID 32576634. Typical Risk.
Blood Cell & Iron Traits
Mean Platelet Volume. Evidence: 10/10. Source: PMID 19221038. Typical Size.
Platelet Count. Evidence: 10/10. Source: PMID 19221038. Typical Count.
Showing effects for C/G genotype
Cardiovascular Risk. Evidence: 4/10. Source: PMID 32576634. Increased Risk.
Mean Platelet Volume. Evidence: 10/10. Source: PMID 19221038. Slightly Larger.
Platelet Count. Evidence: 10/10. Source: PMID 19221038. Slightly Lower.
Showing effects for G/G genotype
Cardiovascular Risk. Evidence: 4/10. Source: PMID 32576634. Highest Risk.
Mean Platelet Volume. Evidence: 10/10. Source: PMID 19221038. Larger Platelets.
Platelet Count. Evidence: 10/10. Source: PMID 19221038. Lower Count.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Inheriting the C/C genotype ensures that the transcription factor EVI1 can bind properly to repress excess PIK3CG gene expression [1]. Because of this normal regulation, platelets remain at a typical size and baseline level of reactivity [2]. Clinical studies show that individuals with this genetic profile have a lower risk of experiencing adverse cardiovascular events, such as complications after coronary stenting [2]. The typical platelet size associated with this genotype also correlates with better long-term outcomes in stroke severity and overall survival [3]. Furthermore, this genotype provides a more stable platelet response during medical challenges, showing less susceptibility to severe drops in platelet counts during certain chemotherapy regimens.
Typical platelet size; Lower risk of clotting complications; Standard platelet counts.
Sample genotype: CG (Heterozygous)
Possessing one copy of the G allele partially disrupts the binding of the EVI1 repressor, leading to moderate increases in PIK3CG gene expression [1]. This genetic shift causes the bone marrow to produce platelets that are slightly larger than average, a measurement known as mean platelet volume [2]. Larger platelets contain more dense granules and are biologically more reactive, which can increase the likelihood of clotting in blood vessels [2]. Consequently, individuals with this heterozygous genotype face a moderately elevated risk of adverse cardiovascular events, particularly after vascular procedures [2]. There is also a slight tendency toward lower overall platelet counts, though the increased activity of the existing platelets outweighs the lower count in terms of clotting risk [3].
Slightly larger platelets; Moderately increased clotting risk; Slightly lower overall platelet count.
Sample genotype: GG (Homozygous)
Carrying the G/G genotype completely disrupts the binding site for the EVI1 repressor, leading to the highest levels of PIK3CG gene expression [1]. This lack of repression causes the bone marrow to release significantly larger platelets into the bloodstream [2]. These oversized platelets are hyper-reactive and bind more readily to form clots, which can restrict blood flow in critical arteries [2]. Clinical evidence links this genotype to the highest risk of adverse cardiac events, especially in patients undergoing coronary interventions [2]. While the overall platelet count is often lower in G/G carriers, the high reactivity of these larger platelets dominates the clinical picture, increasing susceptibility to thrombotic complications [3]. Additionally, this genotype may be associated with a higher risk of severe platelet drops during certain chemotherapy treatments.
Significantly larger platelets; Highest risk of blood clots; Lower baseline platelet count.
Variants with shared genetic architecture
rs342296 · PIK3CG Gene · Chr 7 · Platelet Size and Count
rs12041331 · PEAR1 Gene · Chr 1 · Blood Thinner Response
rs2479409 · PCSK9 Gene · Chr 1 · Cholesterol Levels
The Polygenic and Monogenic Basis of Blood Traits and Diseases.
A novel variant on chromosome 7q22.3 associated with mean platelet volume, counts, and function.
Mean platelet volume and its genetic variants relate to stroke severity and 1-year mortality.
Content updated August 2026.
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