What you carry at this position in your DNA and what research says about it.
Innate Immune Defense: 3/10 evidence, 17 publications.
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Sample genotype (not yours): C/C
Enhanced Innate Immune Protection
This genotype is associated with a reduced risk of Crohn's disease and lower rates of maternal HIV transmission. It supports stronger baseline mucosal defenses.
What this genotype means: Reduced risk of Crohn's disease; Lower risk of mother-to-child HIV transmission; Stronger mucosal defense against Candida.
Sample genotype (not yours): C/G
Typical Innate Immune Protection
This genotype is associated with typical baseline risk for Crohn's disease and maternal HIV transmission. Mucosal defenses operate at standard levels.
What this genotype means: Typical risk of Crohn's disease; Standard maternal HIV transmission risk; Average mucosal defense.
Sample genotype (not yours): G/G
Gene function and biological role
Gene Function: The DEFB1 gene encodes human beta-defensin 1, an antimicrobial peptide that forms a critical component of the body's innate immune system. This peptide is constitutively expressed by epithelial cells lining the respiratory tract, digestive system, skin, and other mucosal barriers [1]. It acts as a natural antibiotic, directly killing a wide range of bacteria, fungi, and viruses [2]. Beyond direct antimicrobial action, beta-defensin 1 serves as a chemical messenger, attracting immune cells like T cells and dendritic cells to sites of infection [1]. Genetic variations in this gene can alter the production of defensins, impacting how effectively the body defends against pathogens and maintains barrier integrity [3].
Variant Impact: The rs1800972 variant, also known as -44 C/G, is located in the 5' untranslated promoter region of the DEFB1 gene. This specific genetic change alters the regulatory region of the gene, affecting how transcription factors bind and initiate the production of beta-defensin 1 [3]. The C allele at this position is associated with altered transcriptional activity and inducibility of the defensin peptide [3]. This variation directly influences the baseline levels of protective defensins present in mucosal linings, such as the gut and oral cavity [3]. Consequently, this single nucleotide change has been linked to susceptibility to chronic inflammatory conditions and infectious diseases [4].
Key Insight: A single letter change in your DNA can alter how your body's natural mucosal barriers defend against both chronic inflammation and viral transmission.
Location: DEFB1. Chromosome 8 · 8p23.1 · 6.9 Mb
Estimated prevalence by population
Global 3.4%; European 4.5%; African 0.7%; East Asian 1.3%; South Asian 2.2%; Americas 5.5%; Ashkenazi 3.6%; Finnish 5.1%; Middle Eastern 1.1%; Amish 6.4%.
Estimated CC genotype frequency.
Global 27.9%; European 33.5%; African 14.9%; East Asian 20.0%; South Asian 25.4%; Americas 35.8%; Ashkenazi 30.6%; Finnish 35.1%; Middle Eastern 18.9%; Amish 37.8%.
Estimated CG genotype frequency.
Global 68.7%; European 61.9%; African 84.5%; East Asian 78.8%; South Asian 72.3%; Americas 58.7%; Ashkenazi 65.9%; Finnish 59.8%; Middle Eastern 80.0%; Amish 55.8%.
Estimated GG genotype frequency.
Showing effects for C/C genotype
Immunity & Inflammation
Chronic Inflammatory Diseases
Crohn's Disease. Evidence: 3/10. Source: PMID 18938660. Reduced Risk.
Infection Susceptibility & Resistance
Mother-to-Child HIV Transmission. Evidence: 3/10. Source: PMID 19390326. Reduced Risk.
Oral Candida Protection. Evidence: 3/10. Source: PMID 19712472. Enhanced Protection.
Cardiovascular & Metabolic
Diabetes & Glycemic Traits
Diabetes Susceptibility. Evidence: 3/10. Source: PMID 25083086. Reduced Risk.
Showing effects for C/G genotype
Crohn's Disease. Evidence: 3/10. Source: PMID 18938660. Typical Risk.
Mother-to-Child HIV Transmission. Evidence: 3/10. Source: PMID 19390326. Typical Risk.
Oral Candida Protection. Evidence: 3/10. Source: PMID 19712472. Typical Protection.
Diabetes Susceptibility. Evidence: 3/10. Source: PMID 25083086. Typical Risk.
Showing effects for G/G genotype
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Epithelial defenses are significantly enhanced by the presence of two protective C alleles. Research indicates this genotype is associated with a significantly reduced risk of developing Crohn's disease, particularly colonic involvement, by maintaining healthy gut barrier function [1]. In infectious contexts, this genetic profile has been linked to a lower risk of mother-to-child HIV transmission and lower viral loads in infected mothers [2]. The variant alters the promoter region of the DEFB1 gene, optimizing the constitutive expression of beta-defensin 1 [3]. This leads to more robust defense against fungal pathogens like Candida in the oral cavity [3]. Additionally, studies suggest this enhanced barrier protection may offer some defense against metabolic stressors and lower susceptibility to type 2 diabetes [4]. Overall, this genotype represents a highly efficient innate immune shield.
Reduced risk of Crohn's disease; Lower risk of mother-to-child HIV transmission; Stronger mucosal defense against Candida.
Sample genotype: CG (Heterozygous)
Standard levels of beta-defensin 1 production are typically maintained by this heterozygous profile. This genetic profile is associated with typical susceptibility to inflammatory bowel conditions like Crohn's disease [1]. It does not provide the heightened protection against maternal HIV transmission observed in those with two copies of the protective allele [2]. Baseline defenses against common oral pathogens like Candida remain at average levels [3]. Similarly, the risk of developing metabolic complications such as type 2 diabetes is consistent with the general population average [4]. While it lacks the extra protective boost of the homozygous minor genotype, it represents a stable, common baseline for immune defense.
Typical risk of Crohn's disease; Standard maternal HIV transmission risk; Average mucosal defense.
Sample genotype: GG (Homozygous)
Representing the most common genetic profile globally, this genotype provides the standard baseline for innate immunity. This genotype is associated with typical susceptibility to inflammatory bowel conditions like Crohn's disease [1]. It does not carry the enhanced protection against maternal HIV transmission seen with the protective variant [2]. Baseline defenses against common oral pathogens like Candida and bacterial colonization operate at average levels [3]. Similarly, the risk of developing metabolic complications such as type 2 diabetes is consistent with the general population average [4]. While it lacks the extra protective boost of the homozygous minor genotype, it represents a stable, common baseline for immune defense.
Variants with shared genetic architecture
rs10761659 · ZNF365 Gene · Chr 10 · Crohn's Disease Risk
rs11209026 · IL23R Gene · Chr 1 · Autoimmune Disease Risk
rs2066845 · NOD2 Gene · Chr 16 · Crohn's Disease Risk
Relevance of α-defensins (HNP1-3) and defensin β-1 in diabetes.
Role of beta-defensin-1 polymorphisms in mother-to-child transmission of HIV-1.
Association of beta-defensin 1 single nucleotide polymorphisms with Crohn's disease.
Content updated August 2026.
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