What you carry at this position in your DNA and what research says about it.
Innate Immune Defense: 8/10 evidence, 17 publications.
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Sample genotype (not yours): C/C
Typical Innate Immune Defense
Two copies of the common allele ensure normal levels of mannose-binding lectin. This supports a robust first-line defense against various pathogens.
What this genotype means: Normal mannose-binding lectin levels; Typical baseline defense against pathogens; Typical risk of autoimmune conditions.
Sample genotype (not yours): C/T
Slightly Reduced Innate Immune Defense
Carrying one copy of the variant allele leads to moderately reduced levels of mannose-binding lectin. This can slightly lower the body's ability to clear certain pathogens.
What this genotype means: Moderately reduced mannose-binding lectin levels; Slightly increased susceptibility to infections; Slightly higher risk of autoimmune conditions.
Sample genotype (not yours): T/T
Significantly Reduced Innate Immune Defense
Two copies of the variant allele cause a severe deficiency of mannose-binding lectin. This can compromise the body's initial defense against infections.
What this genotype means: Severe mannose-binding lectin deficiency; Increased susceptibility to respiratory infections; Higher risk of autoimmune conditions.
Gene function and biological role
Gene Function: The MBL2 gene encodes mannose-binding lectin, a crucial protein in the body's innate immune system [1]. This protein acts as a pattern recognition molecule, identifying and binding to specific sugar patterns on the surfaces of various pathogens like bacteria, viruses, and fungi [1]. Once bound, it activates the complement system to destroy the invaders and helps immune cells engulf them [1]. Genetic variations that lower mannose-binding lectin levels can weaken this first line of defense, making individuals more susceptible to infections [2]. Adequate levels of this protein help maintain robust protection against a wide range of infectious agents [1].
Variant Impact: Replacing the amino acid glycine with aspartic acid at codon 54 disrupts the structure of the mannose-binding lectin protein [1]. This structural change prevents the protein from forming stable, functional multi-protein complexes [1]. As a result, the defective proteins are rapidly degraded, leading to a significant reduction of mannose-binding lectin in the blood [1]. This deficiency impairs the body's ability to recognize and clear pathogens, which has been linked to an increased risk of respiratory infections and autoimmune conditions [3]. The variant is relatively common across many global populations, particularly in those of European and East Asian ancestries [1].
Key Insight: A single amino acid change at codon 54 can cause a 5- to 10-fold reduction in mannose-binding lectin levels, significantly altering how the innate immune system recognizes common pathogens.
Location: MBL2. Chromosome 10 · 10q21.1 · 52.8 Mb
Estimated prevalence by population
Global 78.3%; European 73.8%; African 93.3%; East Asian 69.3%; South Asian 74.6%; Americas 68.5%; Ashkenazi 72.2%; Finnish 72.8%; Middle Eastern 74.6%; Amish 64.7%.
Estimated CC genotype frequency.
Global 20.1%; European 24.3%; African 6.6%; East Asian 27.9%; South Asian 23.5%; Americas 28.6%; Ashkenazi 25.5%; Finnish 25.0%; Middle Eastern 23.5%; Amish 31.5%.
Estimated CT genotype frequency.
Global 1.6%; European 2.0%; African 0.1%; East Asian 2.8%; South Asian 1.9%; Americas 3.0%; Ashkenazi 2.3%; Finnish 2.2%; Middle Eastern 1.9%; Amish 3.8%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Immunity & Inflammation
Inflammatory & Circulating Protein Markers
MBL Protein Levels. Evidence: 8/10. Source: PMID 35078996. Normal Levels.
Infection Susceptibility & Resistance
Respiratory Infection. Evidence: 3/10. Source: PMID 24952212. Typical Risk.
Autoimmune Diseases
Lupus. Evidence: 3/10. Source: PMID 22183303. Typical Risk.
Cardiovascular & Metabolic
Heart Disease
Heart Attack. Evidence: 3/10. Source: PMID 22848725. Typical Risk.
Showing effects for C/T genotype
MBL Protein Levels. Evidence: 8/10. Source: PMID 35078996. Reduced Levels.
Respiratory Infection. Evidence: 3/10. Source: PMID 24952212. Slightly Higher Risk.
Lupus. Evidence: 3/10. Source: PMID 22183303. Slightly Higher Risk.
Heart Attack. Evidence: 3/10. Source: PMID 22848725. Slightly Higher Risk.
Showing effects for T/T genotype
MBL Protein Levels. Evidence: 8/10. Source: PMID 35078996. Deficient Levels.
Respiratory Infection. Evidence: 3/10. Source: PMID 24952212. Higher Risk.
Lupus. Evidence: 3/10. Source: PMID 22183303. Higher Risk.
Heart Attack. Evidence: 3/10. Source: PMID 22848725. Higher Risk.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Normal, functional levels of mannose-binding lectin are produced by those with the CC genotype, supporting a robust innate immune response [1]. This protein effectively recognizes and binds to sugars on the surface of invading microbes, initiating their destruction before a full adaptive immune response is needed [1]. Consequently, a typical, healthy baseline defense against respiratory infections like tuberculosis and pneumonia is maintained [2]. There is also a typical baseline risk for autoimmune conditions such as systemic lupus erythematosus and rheumatoid arthritis [3] [4]. Additionally, normal levels of this lectin are associated with a typical risk of cardiovascular events like myocardial infarction [5]. This standard level of protection helps prevent complications from common pathogens in everyday environments [1]. Ultimately, this genotype represents the standard, protective genetic baseline for innate immunity.
Normal mannose-binding lectin levels; Typical baseline defense against pathogens; Typical risk of autoimmune conditions.
Sample genotype: CT (Heterozygous)
A moderate reduction of functional mannose-binding lectin in the bloodstream occurs with the CT genotype [1]. While many people with this genetic profile remain completely healthy, the lower protein levels can slightly compromise the body's first line of immune defense [2]. This reduction may slightly increase susceptibility to respiratory infections, such as pulmonary tuberculosis, particularly under physical stress or in childhood [2]. There is also a small associated increase in the risk of developing autoimmune conditions like systemic lupus erythematosus and rheumatoid arthritis [3] [4]. Furthermore, some research has linked lower lectin levels to a slightly elevated risk of myocardial infarction [5]. This partial deficiency means the body still produces some functional protein, keeping the overall clinical impact relatively mild for most people [1]. Maintaining general health and wellness can easily offset this minor genetic predisposition.
Moderately reduced mannose-binding lectin levels; Slightly increased susceptibility to infections; Slightly higher risk of autoimmune conditions.
Sample genotype: TT (Homozygous)
Severe deficiency or near-complete absence of functional mannose-binding lectin in the blood characterizes the TT genotype [1]. This deficiency significantly impairs the innate immune system's ability to recognize and clear invading pathogens [1]. Consequently, there is a higher risk of severe respiratory infections, including pulmonary tuberculosis and pneumonia [2]. The lack of functional lectin is also associated with an increased susceptibility to autoimmune disorders such as systemic lupus erythematosus and rheumatoid arthritis [3] [4]. Additionally, research has linked this deficiency to a higher risk of myocardial infarction, potentially due to altered inflammatory responses [5]. While many adults with this genotype live healthy lives, the deficiency is of greater clinical importance during childhood or when the immune system is otherwise compromised [2]. Understanding this status can help explain why some individuals are more prone to recurrent infections.
Severe mannose-binding lectin deficiency; Increased susceptibility to respiratory infections; Higher risk of autoimmune conditions.
Variants with shared genetic architecture
rs5030737 · MBL2 Gene · Chr 10 · Immune and Heart Health
rs1800451 · MBL2 Gene · Chr 10 · MBL Immune Protein
rs7095891 · MBL2 Gene · Chr 10 · Immune System Function
A genome-wide association study of serum proteins reveals shared loci with common diseases.
Content updated August 2026.
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