rs2305480 — GSDMB GSDMB Pro311Ser protective haplotype

Gasdermin B — The Airway Cell Pyroptosis Switch at the Heart of the 17q21 Asthma Locus

The 17q21 chromosomal region is the most replicated genetic risk locus for childhood asthma in the genome, with associations reported across dozens of studies in European, African, East Asian, and South Asian populations. For years, the gene driving this signal was assumed to be ORMDL3¹¹ ORMDL3
ORM1-like protein 3, a transmembrane ER protein that regulates ceramide synthesis and the unfolded protein response, whose expression is tightly regulated by 17q21 variants. But more recent functional work points to its neighbor, GSDMB (gasdermin B), as the causal effector — specifically, GSDMB's ability to trigger pyroptosis²² pyroptosis
A form of inflammatory programmed cell death in which cells release their contents into the surrounding tissue, driving local inflammation — distinct from apoptosis, which is non-inflammatory in airway epithelial cells.

rs2305480 sits within the GSDMB coding sequence on chromosome 17q21. On the plus (genomic) strand, the G allele is the reference, but it is also the risk allele: it encodes a proline at position 311 of the dominant GSDMB isoform, producing a protein with full pyroptotic capacity. The A allele, encoding serine at the same position (p.Pro311Ser), tags a haplotype carrying a protective splice variant (rs11078928) that removes exon 6 and abolishes GSDMB's ability to trigger inflammatory cell death. Most people carry at least one copy of the risk G allele — it is the population-major allele globally — making GG the most common genotype worldwide.

The Mechanism

GSDMB protein belongs to the gasdermin family, which evolved to perforate cell membranes under specific inflammatory conditions. When airway epithelial cells are exposed to viral or bacterial triggers, caspase-1³³ caspase-1
An inflammatory cysteine protease activated by the NLRP3 inflammasome in response to microbial danger signals cleaves GSDMB, releasing its N-terminal domain. This N-terminal fragment inserts into the cell membrane, forming pores that trigger pyroptotic cell death and release pro-inflammatory signals — interleukin-1β (IL-1β), IL-18, and HMGB1 — into the airway.

The splice variant tagged by the protective A allele at rs2305480 removes exon 6, which encodes 13 amino acids within the region essential for GSDMB's pore-forming activity. Without these residues, the protein loses pyroptotic capacity even when caspase-1 cleaves it. Panganiban et al.⁴⁴ Panganiban et al.
J Allergy Clin Immunol, 2018; multi-cohort study combining the GERA cohort and the EVE Consortium (diverse ancestry) showed that the G-allele haplotype (full pyroptotic GSDMB) confers risk while the A-allele haplotype (truncated, non-pyroptotic GSDMB) is protective: combined OR 0.85 (P=1.31×10⁻¹³) in the EVE Consortium.

Beyond pyroptosis, the Das et al. review⁵⁵ Das et al. review
Advances in Immunology, 2017; comprehensive review of 17q21 genes in asthma and immune diseases identified that GSDMB also modulates 5-lipoxygenase (5-LO) expression and TGF-β1 signaling — two further pathways that sustain airway inflammation and promote bronchial remodeling in asthma.

The Evidence

The GABRIEL Consortium GWAS⁶⁶ GABRIEL Consortium GWAS
Moffatt et al., NEJM 2010; 10,365 asthma cases and 16,110 controls from 23 European studies established rs2305480-G as a genome-wide significant risk allele for childhood-onset asthma (OR 1.18, 95% CI 1.11–1.23, P=6×10⁻²³), with an effect specific to childhood-onset disease — no comparable association appeared with adult-onset asthma. This age-specificity is consistent with GSDMB's role in shaping airway epithelial responses during the critical window of early respiratory development.

A Danish GWAS of severe asthma exacerbations⁷⁷ GWAS of severe asthma exacerbations
Bønnelykke et al., Nature Genetics 2014; 1,173 cases aged 2–6 years and 2,522 controls from national health registries identified the GSDMB locus among the strongest hits, with OR 1.32 (95% CI 1.23–1.39), consistent with a larger effect in younger children with more severe disease.

Critically, the signal extends across ancestries. Ober et al.⁸⁸ Ober et al.
Lancet Respiratory Medicine, 2020; expression QTL fine-mapping in African American children found that rs2305480 was the single most robust signal from the 17q21 locus in African Americans (OR 1.36, 95% CI 1.12–1.65, P=0.0014) — and was the most significant eQTL for GSDMB expression in upper airway epithelial cells in this population. This functional eQTL evidence directly links the genetic signal to altered gene expression in the relevant tissue.

A 2025 large-scale study across 13,000+ preschool children⁹⁹ 13,000+ preschool children
Fischer-Rasmussen et al., J Allergy Clin Immunol 2025; discovery in 15 cohorts, replication in 7 additional cohorts up to 5,000 children confirmed rs2305480 as a genome-wide significant determinant of early-onset wheeze (OR 1.26, 95% CI 1.17–1.33, P=2.30×10⁻¹⁶).

In UK asthmatic children, Tulah et al.¹⁰¹⁰ Tulah et al.
BMC Medical Genetics, 2013; 370 UK families with ≥2 asthmatic children showed that the Ser311Pro variant (rs2305480) associated not only with asthma diagnosis but with bronchial hyperresponsiveness and disease severity — indicating it modulates how reactive the airways are to triggers, not merely whether asthma is present.

Practical Actions

The practical implications of rs2305480 center on the early-childhood window when airway inflammatory programming occurs. For GG homozygotes, the key insight is that their airway epithelial cells produce full-activity GSDMB that releases inflammatory signals after respiratory infections — a process that is substantially amplified by environmental tobacco smoke exposure and respiratory viral infections in the first years of life. Actions focus on minimizing inflammatory triggers, optimizing lung function, and ensuring respiratory infections in childhood are treated promptly to limit airway inflammation.

For adults with GG genotype who already have asthma, the GSDMB mechanism suggests that biological triggers of NLRP3 inflammasome activation (respiratory infections, mold exposure, cockroach allergen) may be especially potent triggers compared to the population average.

Interactions

rs2305480 sits within the broader 17q21 asthma susceptibility block, which contains multiple variants in high linkage disequilibrium. The most important functional partners are:

rs11078928 — A splice-region variant that, when in combination with rs2305480-A on the same haplotype, directly removes exon 6 from GSDMB mRNA, eliminating pyroptotic activity. The combined A/A haplotype at these two positions produces the most protective profile.

rs8076131 — An ORMDL3 regulatory variant at the same locus that controls ER stress responses in airway epithelial cells independently of GSDMB. ORMDL3 and GSDMB effects may compound in the same airway cell population.

Gene-environment interaction: 17q21 risk genotype carriers show substantially higher associations between early-life respiratory infections and asthma onset compared to non-carriers, with ORs of 3.42–6.36 versus 1.84–2.44 in those without risk genotypes. Environmental tobacco smoke exposure in early life amplifies this interaction further.