rs1014971 (APOBEC3A): Bladder Cancer Risk Variant

Key takeaways

• rs1014971, on chromosome 22q13.1 near the CBX6 and APOBEC3A genes, is associated with bladder cancer susceptibility at genome-wide significance (p=8x10^-12) across a combined study of more than 11,900 cases and 53,000 controls
• This variant is one of 24 independent genome-wide significant markers used to build a bladder cancer polygenic risk score (a single number summarizing many small genetic contributions to risk), which spans roughly a fourfold difference in estimated lifetime risk between the lowest and highest score decile
• GTEx expression data link this variant to increased activity of APOBEC3B and APOBEC3A in thyroid, lung, and blood, genes encoding cytidine deaminase enzymes whose mutational signatures appear in several cancers
• The locus sits near multiple members of the APOBEC gene family and CBX6; the precise functional mechanism connecting the variant to cancer risk is not established from the available studies
• No specific smoking interaction or lifestyle finding has been reported for this particular variant in the available studies

What the research says rs1014971, on chromosome 22q13.1 near the CBX6 and APOBEC enzyme gene cluster, was first identified as a bladder cancer susceptibility variant in a multi-stage genome-wide association study combining 3,532 cases and 5,120 controls in discovery with 8,381 cases and 48,275 controls in replication, yielding a combined p-value of 8x10^-12 PMID 20972438. At publication, the variant was described as mapping to a non-genic region, though expression quantitative trait locus (eQTL) data - which measure how a variant affects nearby gene activity - now link it to increased APOBEC3B and APOBEC3A expression across multiple tissues GTEx Portal. By 2023, a meta-analysis of 32 international studies incorporating 13,790 cases and 343,502 controls had confirmed 24 independent genome-wide significant bladder cancer loci including this region, constructing a polygenic risk score with an odds ratio of 1.49 per standard deviation (95% CI 1.44-1.53) and approximately fourfold estimated lifetime risk difference between decile extremes PMID 36182614.

Reported associations

• Bladder cancer susceptibility: rs1014971 reached p=8x10^-12 in a combined discovery-plus-replication analysis of 11,913 cases and 53,395 controls across European-ancestry populations PMID 20972438
• Bladder cancer risk (polygenic context): the region contributes to a confirmed 24-marker polygenic risk score with an odds ratio of 1.49 per standard deviation increase (95% CI 1.44-1.53) and roughly fourfold difference in estimated lifetime risk between score deciles, with comparable performance validated in the UK Biobank and PLCO prospective cohorts PMID 36182614

Evidence quality The primary association evidence rests on the Rothman et al. 2010 multi-stage GWAS PMID 20972438, which applied a three-stage replication design across 16 independent studies totaling 11,913 cases and 53,395 controls, reaching p=8x10^-12, well beyond the conventional genome-wide significance threshold of p<5x10^-8. A 2023 meta-analysis of 13,790 cases and 343,502 controls from 32 studies PMID 36182614 confirmed 24 independent genome-wide significant loci and incorporated them into a replicated polygenic risk score, providing large-scale corroboration of the bladder cancer GWAS landscape to which this locus belongs. An independent 2014 GWAS meta-analysis of 6,911 cases and 11,814 controls PMID 25038754 did not list rs1014971 among its primary novel findings in the available text, though it did not explicitly contradict the previously established association. All three studies were restricted to individuals of European ancestry, limiting generalizability to other populations. The GTEx eQTL data provide mechanistic context but were derived from general-population donors without disease and should not be treated as functional proof of the cancer risk mechanism.

Tissue-specific expression effects

• APOBEC3B: the alternate allele is associated with increased expression in thyroid, lung, whole blood, and esophageal mucosa GTEx Portal
• APOBEC3A: the alternate allele is associated with increased expression in thyroid and whole blood GTEx Portal
• ENSG00000305420: the alternate allele is associated with increased expression in thyroid tissue GTEx Portal
• CBX6: the alternate allele is associated with increased expression in pancreas tissue GTEx Portal

Lifestyle considerations No lifestyle considerations on file for this variant.