rs11236797 — LRRC32

Regulatory variant in a distal enhancer at 11q13.5 that controls GARP expression on regulatory T cells, impairing TGF-beta-mediated immune tolerance and increasing risk for asthma, allergic rhinitis, and inflammatory bowel disease

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LRRC32 rs11236797 — The Regulatory T Cell Tolerance Switch

Regulatory T cells (Tregs) are the immune system's peacekeepers — specialized lymphocytes that suppress excessive inflammation and prevent the immune system from attacking harmless environmental antigens like pollen, pet dander, and food proteins. Their ability to do this depends critically on a surface protein called GARP11 GARP
Glycoprotein A repetitions predominant, encoded by LRRC32. Also known as LRRC32 (leucine-rich repeat containing 32). Essential for anchoring latent TGF-beta on the Treg surface.. rs11236797 sits in a distal enhancer element at chromosome 11q13.5 that controls how much GARP your Tregs produce. The risk A allele weakens this enhancer, reducing GARP expression and — with it — the Tregs' capacity to enforce immune tolerance. The result is a measurably elevated risk for asthma, allergic rhinitis, hay fever, and inflammatory bowel disease.

The Mechanism

GARP functions as a docking receptor for latent TGF-beta22 docking receptor for latent TGF-beta
TGF-beta (transforming growth factor-beta) is produced as an inactive precursor tethered to a latency-associated peptide. GARP anchors this complex to the Treg surface, positioning it for integrin-mediated activation on the Treg cell surface. When a Treg contacts an inflammatory cell through T-cell receptor signaling, surface-bound latent TGF-beta is converted to its active form. The activated TGF-beta then suppresses nearby effector T cells, mast cells, and innate immune cells — the cellular machinery behind allergic reactions.

The enhancer containing rs11236797 recruits the transcription factors STAT5 and NF-κB33 STAT5 and NF-κB
STAT5 responds to cytokines like IL-2 that maintain Treg survival; NF-κB responds to inflammatory signals, ensuring GARP is upregulated precisely when Tregs need to suppress inflammation to drive signal-dependent LRRC32 expression. In a landmark 2020 Nature study, Nasrallah et al. demonstrated that human Treg cells carrying risk variants at this locus show reduced histone acetylation at the enhancer and lower GARP protein levels44 reduced histone acetylation at the enhancer and lower GARP protein levels
Histone acetylation is an epigenetic mark of active gene regulatory elements; reduced acetylation means the enhancer is less open and less active, producing less GARP mRNA and protein. Mice lacking this enhancer entirely retained viable Treg cells — but those Tregs were unable to control colitis in cell-transfer experiments, directly demonstrating that GARP loss impairs Treg suppressor function without abolishing Tregs altogether.

The Evidence

The earliest genome-wide signal at this locus came from a 2011 Lancet study by Ferreira et al.55 2011 Lancet study by Ferreira et al.
Australian Asthma Genetics Consortium, n=57,800 combined that identified 11q13.5/LRRC32 as a genome-wide significant asthma risk locus (OR=1.09, p=1.8×10⁻⁸), with a stronger signal specifically for atopic asthma (OR=1.33, p=7×10⁻⁴), consistent with the locus acting through allergic sensitization rather than non-allergic airway inflammation.

The most comprehensive allergic disease GWAS to date — Ferreira et al. Nature Genetics 201766 Ferreira et al. Nature Genetics 2017
360,838 participants from the UK Biobank and international cohorts; 136 independent genome-wide significant loci identified, 73 novel; 23andMe was a major contributing cohort — confirmed 11q13.5 as a shared risk locus for asthma, hay fever, and eczema. Most loci in this study act across all three allergic conditions, underscoring that allergic diseases share more genetic architecture than they differ. The GWAS Catalog records associations for rs11236797-A with asthma (OR=1.12, p=6×10⁻⁶²), childhood-onset asthma (OR=1.16, p=1×10⁻⁹³), allergic rhinitis (OR=1.14, p=5×10⁻³²), and inflammatory bowel disease (p=7×10⁻³³), pointing to a broadly immunoregulatory locus rather than a disease-specific one.

The mechanistic connection was established by the 2020 Nature study from Nasrallah et al.77 2020 Nature study from Nasrallah et al.
Functional genomics in 91–123 healthy human donors, confirmed in mouse enhancer-knockout models, which linked the disease-associated enhancer directly to GARP expression in human Tregs — bridging the gap between GWAS signals and biological function.

Practical Actions

The A allele does not eliminate Treg function — it reduces the efficiency of Treg-mediated suppression at the molecular level. This has practical implications: environmental and lifestyle factors that support Treg numbers and function can partially offset the genetic disadvantage.

Vitamin D promotes Treg differentiation and upregulates FoxP3, the master transcription factor for Treg identity. Maintaining adequate 25-OH vitamin D levels supports Treg biology across multiple pathways. Probiotic strains with documented Treg-supporting effects — particularly those used in clinical allergy studies — can expand peripheral Treg populations in the gut mucosa, the site where much of the GARP-dependent immunosuppression operates.

The IBD association for this locus is particularly meaningful: the gut is where GARP-expressing Tregs are most densely deployed for mucosal tolerance. Carriers of the A allele who have digestive symptoms, a family history of IBD, or significant allergic disease burden may benefit from earlier gastroenterological evaluation.

Interactions

rs11236797 (LRRC32/GARP) and rs17293632 (SMAD3) operate in the same TGF-beta tolerance pathway: GARP activates latent TGF-beta on the Treg surface; SMAD3 is the primary intracellular signal transducer that TGF-beta activates inside target cells. Reduced GARP (this variant) and reduced SMAD3 (rs17293632) would compound to impair TGF-beta signal initiation and propagation. Both variants are associated with asthma and IBD. The combination of risk alleles at both loci represents a compound Treg tolerance defect that no single-genotype analysis captures.

Genotype Interpretations

What each possible genotype means for this variant.

CC Full Treg Suppressor Function Normal

Full GARP expression; normal Treg-mediated immune tolerance and allergic disease risk

You carry two copies of the C allele at rs11236797, meaning your 11q13.5 enhancer operates at full activity. Your regulatory T cells produce GARP at normal levels, allowing efficient anchoring and activation of TGF-beta on the Treg surface. Your immune system's capacity for Treg-mediated tolerance is intact, and your genetic risk for asthma, hay fever, eczema, and inflammatory bowel disease through this locus is at population baseline. This is the most common genotype globally, carried by approximately 35% of people. Among European populations about 31% carry this genotype; it is more common in African populations (~55%) where the A risk allele is less frequent.

AC Reduced Treg GARP Expression Intermediate

One copy of the risk allele; moderately reduced GARP on regulatory T cells and mildly elevated allergic disease susceptibility

The 11q13.5 enhancer containing rs11236797 normally recruits STAT5 and NF-κB to drive LRRC32 transcription in Tregs. Carrying one A allele reduces histone acetylation at the enhancer on that chromosome, partially lowering GARP expression. With reduced GARP on the Treg surface, fewer latent TGF-beta complexes are anchored — meaning Tregs are somewhat less effective at suppressing nearby effector cells responding to allergens or intestinal antigens. The additive inheritance pattern means a single A allele confers a proportional but moderate effect, intermediate between CC and AA.

AA Impaired Treg Tolerance High Risk

Two copies of the risk allele; substantially reduced GARP expression on regulatory T cells and elevated risk for asthma, allergic rhinitis, and inflammatory bowel disease

With both enhancer copies carrying the A allele, LRRC32 transcription in Tregs is reduced on both chromosomes. The 2020 Nature paper by Nasrallah et al. showed that risk variants at this locus directly reduce histone H3K27 acetylation — a mark of active regulatory elements — at the enhancer in human Tregs from healthy donors, and that GARP protein levels are correspondingly lower. In mouse models, complete loss of the enhancer produced Tregs that were unable to suppress colitis in adoptive transfer experiments, even though Treg numbers were intact. Homozygous AA individuals represent the closest human analog: quantitatively reduced GARP with intact Treg counts, but functionally impaired suppression. The broad GWAS associations across allergic and intestinal inflammatory conditions are consistent with this pan-tolerance defect: the same Treg suppression mechanisms that prevent asthma and hay fever in the lung also prevent colitis in the gut.