What you carry at this position in your DNA and what research says about it.
Immune Cell Levels: 10/10 evidence, 40 publications.
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Sample genotype (not yours): C/C
Typical Immune Cell Levels and Liver Enzymes
This genotype is associated with typical to slightly higher white blood cell and neutrophil counts. It is also linked to slightly lower baseline liver enzyme levels.
What this genotype means: Typical white blood cell count; Slightly lower liver enzymes; Typical testosterone levels.
Sample genotype (not yours): C/T
This genotype represents an intermediate profile, resulting in typical white blood cell counts and standard liver enzyme levels.
What this genotype means: Typical white blood cell count; Typical liver enzyme levels; Typical metabolic markers.
Sample genotype (not yours): T/T
Slightly Lower Immune Cells and Higher Liver Enzymes
This genotype is linked to slightly lower white blood cell counts and slightly higher baseline liver enzyme levels.
What this genotype means: Slightly lower white blood cell count; Slightly higher baseline liver enzymes; Slightly higher total cholesterol.
Gene function and biological role
Gene Function: The CDK6 gene encodes cyclin-dependent kinase 6, a crucial protein that regulates the cell cycle and cell division [1]. It is highly active in the bone marrow, where it helps control the development and maturation of various blood cells from stem cells [2]. By interacting with specific transcription factors, this protein plays a key role in determining when immune progenitor cells differentiate into mature white blood cells [2]. Beyond blood cell production, it is also involved in broader cellular processes, including tumor growth and the body's inflammatory response [1].
Variant Impact: The rs445 variant is located in an intron, or non-coding region, of the CDK6 gene and acts as a key genetic regulator of its expression. This genetic change influences how efficiently the gene is read, directly affecting the production of white blood cells in the bone marrow [2]. Specifically, the C allele is associated with higher levels of myeloid immune cells, such as neutrophils and monocytes, while the T allele is linked to lower levels [2]. Because of its direct impact on these immune cells, researchers often use this variant as a genetic proxy to study the effects of CDK6-inhibiting medications [3].
Key Insight: This variant acts as a natural genetic dial for white blood cell counts, and researchers use it to study how the body might respond to certain cancer therapies.
Location: CDK6. Chromosome 7 · 7q21.2 · 92.8 Mb
Estimated prevalence by population
Global 73.8%; European 80.0%; African 65.8%; East Asian 42.9%; South Asian 76.4%; Americas 70.3%; Ashkenazi 62.6%; Finnish 89.1%; Middle Eastern 47.7%; Amish 82.2%.
Estimated CC genotype frequency.
Global 23.8%; European 18.9%; African 30.7%; East Asian 45.2%; South Asian 22.0%; Americas 27.1%; Ashkenazi 33.1%; Finnish 10.6%; Middle Eastern 42.7%; Amish 16.9%.
Estimated CT genotype frequency.
Global 2.4%; European 1.1%; African 3.6%; East Asian 11.9%; South Asian 1.6%; Americas 2.6%; Ashkenazi 4.4%; Finnish 0.3%; Middle Eastern 9.6%; Amish 0.9%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Blood Cell & Iron Traits
White Blood Cell Count. Evidence: 10/10. Source: PMID 27863252. Slightly Higher.
Neutrophil Count. Evidence: 10/10. Source: PMID 21738478. Slightly Higher.
Lipids & Cholesterol
Total Cholesterol. Evidence: 9/10. Source: PMID 30275531. Slightly Lower.
Organ Systems
Liver Function & Disease
Liver Enzyme Levels. Evidence: 9/10. Source: PMID 33462484. Slightly Lower.
Endocrine & Reproductive
Hormone Levels & Endocrine Regulation
Testosterone Levels. Evidence: 8/10. Source: PMID 32042192. Slightly Higher.
Showing effects for C/T genotype
White Blood Cell Count. Evidence: 10/10. Source: PMID 27863252. Typical.
Neutrophil Count. Evidence: 10/10. Source: PMID 21738478. Typical.
Total Cholesterol. Evidence: 9/10. Source: PMID 30275531. Typical.
Liver Enzyme Levels. Evidence: 9/10. Source: PMID 33462484. Typical.
Testosterone Levels. Evidence: 8/10. Source: PMID 32042192. Typical.
Showing effects for T/T genotype
White Blood Cell Count. Evidence: 10/10. Source: PMID 27863252. Slightly Lower.
Neutrophil Count. Evidence: 10/10. Source: PMID 21738478. Slightly Lower.
Total Cholesterol. Evidence: 9/10. Source: PMID 30275531. Slightly Higher.
Liver Enzyme Levels. Evidence: 9/10. Source: PMID 33462484. Slightly Higher.
Testosterone Levels. Evidence: 8/10. Source: PMID 32042192. Slightly Lower.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Carrying two copies of the C allele is the most common genetic profile globally. This profile is associated with typical levels of white blood cells, particularly neutrophils, which serve as the body's first line of defense against infections [1]. Studies show that individuals with this genotype tend to have slightly higher baseline counts of these myeloid immune cells compared to those carrying the T allele [1]. Additionally, this genetic makeup is linked to slightly lower levels of liver enzymes such as ALT and GGT, indicating typical liver function marker baselines [2]. There is also a minor association with slightly higher testosterone and sex hormone-binding globulin levels [3]. Overall, these variations represent normal physiological diversity and do not indicate any health risks or medical conditions.
Typical white blood cell count; Slightly lower liver enzymes; Typical testosterone levels.
Sample genotype: CT (Heterozygous)
Carrying one copy of the C allele and one copy of the T allele provides a balanced genetic influence on blood cell production. This intermediate profile typically results in standard levels of white blood cells, including neutrophils and monocytes [1]. Because this genotype sits between the two homozygous profiles, immune cell counts generally fall right in the middle of the population average [1]. Similarly, baseline levels of liver enzymes such as ALT, AST, and GGT remain within the typical, healthy range [2]. Metabolic markers, including total cholesterol and hormone levels, also show standard baseline values [3]. These subtle genetic influences contribute to normal physiological variation without impacting overall health or disease susceptibility. No specific lifestyle or medical adjustments are associated with this common genetic profile.
Typical white blood cell count; Typical liver enzyme levels; Typical metabolic markers.
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele is associated with a minor reduction in baseline white blood cell and neutrophil counts [1]. While these levels are slightly lower than the population average, they generally remain within the normal, healthy range and do not imply an impaired immune system [1]. This genetic profile is also linked to slightly higher baseline levels of liver enzymes, including ALT, AST, and GGT [2]. Additionally, research indicates a minor association with slightly higher total cholesterol levels [3]. These subtle differences represent natural genetic variation rather than active disease states. Understanding these baseline tendencies can help put routine blood test results into a clearer personal context.
Slightly lower white blood cell count; Slightly higher baseline liver enzymes; Slightly higher total cholesterol.
Variants with shared genetic architecture
rs2282978 · CDK6 Gene · Chr 7 · Blood Pressure and Height
rs4272 · CDK6 Gene · Chr 7 · Rheumatoid Arthritis Risk
rs42041 · CDK6 Gene · Chr 7 · Autoimmune and Joint Health
The Allelic Landscape of Human Blood Cell Trait Variation and Links to Common Complex Disease.
Genetics of 35 blood and urine biomarkers in the UK Biobank.
Using human genetics to understand the disease impacts of testosterone in men and women.
Content updated August 2026.
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