rs2976388 — PSCA PSCA bladder urothelial variant

PSCA Urothelial Variant — A Bladder Lining Gene That Shapes UTI Risk in Women

PSCA¹¹ PSCA
Prostate stem cell antigen — despite the name, this GPI-anchored glycoprotein is broadly expressed across epithelial tissues including bladder urothelium, gastric mucosa, and pancreatic ducts; it belongs to the Ly-6/uPAR superfamily and regulates cell adhesion, proliferation, and the mucosal response to bacteria lines the inner surface of the bladder and is thought to help maintain urothelial integrity against bacterial attachment. The rs2976388 variant sits deep within an intron of the PSCA gene at chromosome 8, position 142,678,838 (GRCh38). It does not change the protein sequence, but it lies within a region of active regulatory chromatin — specifically within enhancers defined in epidermal and epithelial keratinocytes — and is in strong linkage disequilibrium²² linkage disequilibrium
LD — the tendency of nearby variants to be inherited together; high LD means the two SNPs almost always occur together on the same chromosome, so one serves as a reliable proxy for the other with rs2294008, a functional variant in the PSCA 5′ UTR with established effects on gene expression.

The Mechanism

The G allele at rs2976388 tags a regulatory haplotype that influences PSCA expression in epithelial tissues. The variant overlaps strong enhancer marks in urothelial keratinocyte epigenome data, suggesting it may modulate enhancer activity in the bladder epithelium. Because rs2976388 is in tight LD with rs2294008 — the variant that creates a YY1 repressor binding site suppressing PSCA transcription — carrying the rs2976388 G allele effectively marks the same suppressive haplotype at the PSCA locus. Less PSCA on the urothelial surface may impair the epithelial barrier that normally restricts bacterial adherence. The female-specificity of the UTI association (see below) is biologically coherent: women have a substantially shorter urethra and a higher anatomical exposure of the bladder to gut-origin uropathogens, making urothelial surface molecule expression a more decisive factor in bacterial containment than in men.

PSCA's role in peptic ulcer disease — also associated with this variant (OR 1.09 for the G allele) — reinforces the gene's function across epithelial barrier tissues and suggests a shared mechanism of reduced surface PSCA compromising mucosal protection in both the stomach and bladder.

The Evidence

The primary association was established in a 23andMe genome-wide study³³ 23andMe genome-wide study
Tian C et al. Genome-wide association and HLA region fine-mapping studies identify susceptibility loci for multiple common infections. Nature Communications, 2017 of 23 infection phenotypes in over 200,000 individuals of European ancestry. For urinary tract infection frequency, rs2976388 reached genome-wide significance with a beta of 0.04 and p = 3.27 × 10⁻¹⁰. Crucially, when the authors stratified by sex, the association was highly significant in women (P < 1 × 10⁻¹¹) but completely absent in men (P > 0.1) — a sex-specific effect with a difference of more than ten orders of magnitude in statistical evidence. This pattern is consistent with the known epidemiology of UTI: uropathogenic E. coli infections are approximately 30-fold more common in women than men, and urothelial surface antigen expression is a plausible modifier of that pre-existing anatomical vulnerability.

A second independent GWAS for peptic ulcer disease⁴⁴ GWAS for peptic ulcer disease
Wu et al. GWAS of peptic ulcer disease implicates Helicobacter pylori infection, other gastrointestinal disorders and depression. Nature Communications, 2021 identified the same G allele at rs2976388 with OR 1.09 and p = 2 × 10⁻¹⁴, extending PSCA's role as a shared mucosal vulnerability gene across gastroduodenal and urological epithelia.

For the closely linked rs2294008 and rs2978974 variants (bladder cancer), a PNAS study⁵⁵ PNAS study
Fu YP et al. Common genetic variants in the PSCA gene influence gene expression and bladder cancer risk. PNAS, 2012 showed that the PSCA risk haplotype increases PSCA mRNA expression in bladder tumour tissue and independently confers bladder cancer susceptibility. Because rs2976388 tags the same haplotype block, it is co-inherited with both the UTI and bladder cancer risk signals at this locus.

Practical Implications

For women with the GG or AG genotype, the clearest interventions are those that reduce uropathogen adherence to the urothelium. The mechanistic basis of D-mannose is direct: it saturates the FimH lectin⁶⁶ FimH lectin
The tip adhesin of type 1 pili on uropathogenic E. coli; FimH binds mannose residues on urothelial uroplakin proteins; free D-mannose competes for binding and prevents bacterial attachment to the bladder wall on uropathogenic E. coli, preventing the bacteria from anchoring to bladder wall glycoproteins. In an RCT of 308 women⁷⁷ RCT of 308 women
Kranjčec B et al. D-mannose powder for prophylaxis of recurrent urinary tract infections in women. World J Urol, 2014, daily D-mannose reduced recurrent UTI from 60.8% to 14.6% over six months — a result comparable to continuous nitrofurantoin prophylaxis but without antibiotic resistance consequences.

Cranberry A-type proanthocyanidins (PACs) provide a complementary anti-adhesion mechanism targeting P-fimbriated E. coli (distinct from the FimH pathway). A meta-analysis⁸⁸ meta-analysis
Fu Z et al. Cranberry Reduces the Risk of Urinary Tract Infection Recurrence in Otherwise Healthy Women. J Nutrition, 2017 of 7 RCTs (1,498 women) found a 26% reduction in UTI recurrence (pooled RR 0.74, 95% CI 0.55–0.98). High-dose standardized cranberry extract (36 mg PACs daily) is more consistently effective than cranberry juice, which contains highly variable PAC concentrations.

Interactions

The rs2976388 G allele is in strong linkage disequilibrium with rs2294008 (PSCA 5′ UTR), the functional variant that suppresses PSCA expression through YY1 repressor recruitment. Individuals carrying the G allele at rs2976388 very likely also carry the T allele at rs2294008. Users who appear in both the innate-immunity category (this SNP) and the gut-digestive category (rs2294008) are carrying the same underlying risk haplotype; the rs2294008 entry covers gastric cancer and H. pylori implications in detail, while this entry focuses on the urothelial manifestation.

The second bladder cancer signal at rs2978974 (PSCA intron 2) contributes a multiplicative effect on bladder cancer risk that is independent of rs2294008, per the Fu et al. 2012 PNAS analysis. The UTI phenotype was mapped specifically to rs2976388 in the Tian et al. 2017 GWAS; whether rs2978974 similarly modifies UTI risk has not been tested.