The most common primary immunodeficiency, usually mild or symptom-free — a 2016 GWAS named four risk loci directly in its title, one of them the ATG13/AMBRA1 region represented on this page.
Selective IgA deficiency is a low or absent level of immunoglobulin A, the antibody that guards mucosal surfaces (gut, airways). It is the most common primary immunodeficiency, and most people who have it are mild or entirely symptom-free; a minority have recurrent sinus and respiratory infections or an elevated rate of autoimmune conditions.
This 2016 study compared 1,635 European-ancestry cases against 4,852 controls, and its own title names four associated loci: PVT1, ATG13-AMBRA1, AHI1 and CLEC16A. rs4565870, in the ATG13/AMBRA1 region, is one of them: each copy of the risk allele (C) was associated with roughly 1.38 times the odds of selective IgA deficiency (p=7×10⁻¹⁰). ATG13 and AMBRA1 are both involved in autophagy, the cell's internal recycling and quality-control process — several of the genes this study implicated have roles in immune cell regulation more broadly, consistent with an autoimmune-adjacent mechanism for at least some cases.
Selective IgA deficiency is diagnosed by a blood test measuring IgA levels directly — not by genotype. rs4565870 is not used by any guideline to diagnose the condition or decide treatment in an individual.
Most people with selective IgA deficiency need no treatment at all. Those with recurrent infections may be managed with prompt antibiotic treatment of infections as they occur; unlike some other antibody deficiencies, standard immunoglobulin replacement therapy is not used, both because it is not usually needed and because of a small but real risk of a severe reaction in some IgA-deficient people who have developed anti-IgA antibodies. The variant on this page describes population-level genetic risk, not an individual diagnostic marker.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about Selective IgA Deficiency comes down to these specific, well-studied positions — not a diagnosis.
Databases, guidelines and references
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Selective IgA Deficiency. MyGeneLog™. https://www.mygenelog.com/conditions/selective-iga-deficiency
Selective IgA deficiency is a low or absent level of immunoglobulin A, the most common primary immunodeficiency. Most people who have it are mild or entirely symptom-free.
Comparing 1,635 cases against 4,852 controls, it found four associated loci named directly in its own title: PVT1, ATG13-AMBRA1, AHI1 and CLEC16A. The variant on this page, in the ATG13/AMBRA1 region, was linked to roughly 1.38 times the odds of the condition per risk allele copy.
No. This is a population-level risk association from a research study, not a diagnosis. Selective IgA deficiency is diagnosed with a blood test measuring IgA levels directly.
Most people need no treatment. Those with recurrent infections are managed with prompt antibiotic treatment as infections occur -- standard immunoglobulin replacement is not used, both because it is usually unnecessary and because of a small risk of severe reaction in some IgA-deficient people with anti-IgA antibodies.
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