What you carry at this position in your DNA and what research says about it.
G6PD Deficiency: 7/10 evidence, 23 publications.
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Sample genotype (not yours): C/C
Normal G6PD Enzyme Activity
Two copies of the normal C allele provide full protection against oxidative stress in red blood cells. There is no elevated risk of G6PD deficiency or drug-induced hemolytic anemia.
What this genotype means: Normal G6PD enzyme levels; Standard HbA1c test accuracy; Typical red blood cell lifespan.
Sample genotype (not yours): C
A single copy of the normal C allele in males provides full G6PD enzyme function. There is no elevated risk of G6PD deficiency or drug-induced hemolytic anemia.
Sample genotype (not yours): C/T
Malaria Protection and Drug Sensitivity
Possessing one normal and one variant allele provides partial protection against malaria but introduces mild drug sensitivities. Measured HbA1c levels may be slightly lower than actual blood sugar levels reflect.
What this genotype means: Partial malaria resistance; Slightly underestimated HbA1c; Potential sensitivity to oxidative drugs.
Sample genotype (not yours): T
G6PD Deficiency and High Anemia Risk
A single copy of the variant T allele in males causes G6PD deficiency, making red blood cells highly sensitive to oxidative stress. Certain medications, fava beans, and infections can trigger acute hemolytic anemia.
What this genotype means: High risk of hemolytic anemia; Significantly underestimated HbA1c; Severe sensitivity to oxidative medications.
Sample genotype (not yours): T/T
Two copies of the variant T allele cause G6PD deficiency, making red blood cells highly sensitive to oxidative stress. Certain medications, fava beans, and infections can trigger acute hemolytic anemia.
Gene function and biological role
Gene Function: The G6PD gene encodes glucose-6-phosphate dehydrogenase, an essential enzyme that protects red blood cells from oxidative damage [1]. This enzyme is a key component of the pentose phosphate pathway, producing NADPH to maintain cellular antioxidants [2]. When G6PD activity is compromised, red blood cells become highly vulnerable to premature destruction under oxidative stress [3]. Because the gene is located on the X chromosome, its inheritance and clinical presentation differ significantly between males and females [4].
Variant Impact: The rs1050828 variant, also known as the Asahi or G202A mutation, is a missense change that alters the amino acid at position 68 from valine to methionine [1]. This molecular alteration reduces the stability and overall activity of the G6PD enzyme in red blood cells [5]. The variant is highly prevalent in populations of African ancestry, where it is a primary driver of the G6PD A- deficiency phenotype [3]. In addition to causing enzyme deficiency, this variant significantly alters several standard red blood cell measurements [6].
Key Insight: This variant artificially lowers HbA1c levels, which can cause standard diabetes screening tests to miss an active type 2 diabetes diagnosis.
Location: G6PD. Chromosome X · Xq28 · 154.5 Mb
Origin Story: The G6PD A- mutation rose to high frequency in sub-Saharan Africa because it provides robust protection against severe malaria infections.
Estimated prevalence by population
Global 93.7%; European > 99.9%; African 78.2%; East Asian 100.0%; South Asian 99.9%; Americas 97.6%; Ashkenazi 100.0%; Finnish 100.0%; Middle Eastern 99.1%; Amish 100.0%.
Estimated CC genotype frequency.
Global 5.9%; European < 0.1%; African 20.5%; East Asian 0.0%; South Asian 0.1%; Americas 2.4%; Ashkenazi 0.0%; Finnish 0.0%; Middle Eastern 0.9%; Amish 0.0%.
Estimated CT genotype frequency.
Global 0.4%; European < 0.1%; African 1.3%; East Asian 0.0%; South Asian < 0.1%; Americas < 0.1%; Ashkenazi 0.0%; Finnish 0.0%; Middle Eastern < 0.1%; Amish 0.0%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Rare Genetic Disorders
Inherited Metabolic Disorders
G6PD Deficiency. Evidence: 7/10. Source: PMID 11852882.
Cardiovascular & Metabolic
Diabetes & Glycemic Traits
HbA1c Accuracy. Evidence: 10/10. Source: PMID 28898252.
Immunity & Inflammation
Infection Susceptibility & Resistance
Malaria Resistance. Evidence: 5/10. Source: PMID 23614351.
Pharmacogenomics
Drug Metabolism Enzyme Activity
Drug Sensitivity. Evidence: 8/10. Source: PMID 20194698.
Showing effects for C genotype
Showing effects for C/T genotype
Showing effects for T genotype
Showing effects for T/T genotype
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Normal G6PD enzyme levels ensure that red blood cells can efficiently neutralize oxidative compounds [1]. This genotype is associated with typical red blood cell counts and standard HbA1c measurement accuracy [2]. Standard diabetes screening using HbA1c remains highly reliable without genetic adjustment [3]. There is no genetic sensitivity to oxidative medications like dapsone or primaquine [4]. Red blood cells maintain a typical lifespan and do not undergo premature destruction under normal physiological conditions [1].
Normal G6PD enzyme levels; Standard HbA1c test accuracy; Typical red blood cell lifespan.
Sample genotype: C (Single copy)
Full G6PD enzyme activity protects red blood cells from premature destruction under oxidative stress [1]. Red blood cell counts, volume, and lifespan are typical and unaffected by genetic deficiency [2]. Standard HbA1c measurements accurately reflect average blood sugar levels over the preceding months [3]. There is no genetic sensitivity to oxidative medications, allowing for standard prescribing of drugs like dapsone or primaquine [4]. Red blood cells maintain a typical lifespan and do not undergo premature destruction under normal physiological conditions [1].
Sample genotype: CT (Heterozygous)
A mosaic of normal and deficient red blood cells is present due to random X-chromosome inactivation [1]. This mixed population of cells provides significant resistance to severe malaria infections [2]. However, exposure to strong oxidative medications like dapsone or primaquine can still trigger mild hemolytic episodes [3]. Measured HbA1c levels are typically underestimated by approximately 0.26% to 0.35% units, which can lead to missed prediabetes or diabetes diagnoses [4].
Partial malaria resistance; Slightly underestimated HbA1c; Potential sensitivity to oxidative drugs.
Sample genotype: T (Single copy)
Severely reduced G6PD enzyme activity compromises the antioxidant defenses of red blood cells [1]. Exposure to oxidative triggers causes rapid destruction of red blood cells, leading to acute hemolytic anemia [2]. Standard HbA1c measurements are artificially lowered by roughly 0.79% to 0.88% units, meaning diabetes screening using HbA1c alone is highly unreliable [3]. Alternative glycemic markers or direct glucose measurements must be used for accurate diabetes evaluation [3]. Avoiding known oxidative drugs, such as primaquine and nitrofurantoin, is critical to preventing hemolytic crises [4].
High risk of hemolytic anemia; Significantly underestimated HbA1c; Severe sensitivity to oxidative medications.
Sample genotype: TT (Homozygous)
Severely reduced G6PD enzyme activity compromises the antioxidant defenses of red blood cells [1]. Exposure to oxidative triggers causes rapid destruction of red blood cells, leading to acute hemolytic anemia [2]. Standard HbA1c measurements are artificially lowered by roughly 0.67% to 0.88% units, meaning diabetes screening using HbA1c alone is highly unreliable [3]. Alternative glycemic markers or direct glucose measurements must be used for accurate diabetes evaluation [3]. Avoiding known oxidative drugs, such as primaquine and nitrofurantoin, is critical to preventing hemolytic crises [4].
Variants with shared genetic architecture
rs5030868 · G6PD Gene · Chr X · G6PD Deficiency Risk
rs72554665 · G6PD Gene · Chr X · G6PD Deficiency Risk
rs1050829 · G6PD Gene · Chr X · G6PD Enzyme Type
Molecular heterogeneity of glucose-6-phosphate dehydrogenase A-.
Both mutations in G6PD A- are necessary to produce the G6PD deficient phenotype.
Genetic determinants of glucose-6-phosphate dehydrogenase activity in Kenya.
The genetic risk of acute seizures in African children with falciparum malaria.
Content updated August 2026.
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