rs2075570 — MUC1 Near gene

MUC1 Region Variant rs2075570 — A Gastric Cancer Susceptibility Marker at 1q22

Chromosome 1q22 is one of the most consistently replicated gastric cancer susceptibility regions in the human genome. rs2075570 is an intronic variant¹¹ intronic variant
Located within intron 2 of MTX1 (metaxin 1), about 50 kb from MUC1's transcription start site that serves as a tag SNP for this locus — a marker in tight linkage disequilibrium²² linkage disequilibrium
Linkage disequilibrium means two variants are co-inherited so frequently that knowing one predicts the other with functional variants that directly regulate the expression of genes critical for gastric mucosal defense. It was co-identified with rs2070803 in the first gastric cancer genome-wide association study performed in a Japanese population and has since been replicated across Chinese, Korean, and other East Asian cohorts.

The Mechanism

rs2075570 itself does not change any protein sequence — it is an intronic variant in MTX1 with no direct functional consequence. Its significance lies in what it tags. Fine-mapping of the 64.8 kb high-LD block containing rs2075570 identified two functional germline enhancer variants³³ germline enhancer variants
Germline variants present in every cell from birth, inherited from parents — rs2049805-C and rs2974931-G — that reside in an active chromatin region. These variants strengthen enhancer activity, which in turn upregulates the expression of UBAP2L (ubiquitin-associated protein 2-like)⁴⁴ UBAP2L (ubiquitin-associated protein 2-like)
UBAP2L promotes cell proliferation and invasion; its overexpression in gastric cancer tissue correlates with worse patient survival over a remarkable 960 kb chromatin loop distance. The 1q22 block simultaneously encompasses MUC1⁵⁵ MUC1
Mucin-1 protects the gastric epithelium by blocking H. pylori adhesion and maintaining mucus barrier integrity, whose own functional variant rs4072037 operates through a distinct splicing mechanism — meaning rs2075570 marks a region where at least two independent biological pathways converge to shape gastric cancer risk.

The Evidence

The original Japanese GWAS identified the 1q22 region defined by rs2075570 and rs2070803 at P~1×10⁻⁷. Meta-analysis of Japanese and Korean populations⁶⁶ Meta-analysis of Japanese and Korean populations
Saeki et al., Gastroenterology 2011; confirmed across multiple East Asian cohorts yielded OR=1.71 (P=2.3×10⁻¹²) for gastric cancer, placing this among the strongest common-variant associations for this malignancy. A field synopsis and meta-analysis⁷⁷ field synopsis and meta-analysis
Mocellin et al., Gut 2015, the most comprehensive systematic review of gastric cancer susceptibility variants rated rs2075570 as one of 11 high-evidence biomarkers — the highest tier based on multiple large replicated studies. The association is specific to diffuse-type gastric cancer⁸⁸ diffuse-type gastric cancer
Diffuse gastric cancer is the more aggressive subtype, often presenting at advanced stage and lacking the intestinal precursor lesions that permit earlier detection, not intestinal-type, suggesting the underlying pathway relates to mucosal barrier integrity and submucosal invasion rather than to gastric acid secretion and intestinal metaplasia. A survival analysis of GC cases at high-evidence susceptibility loci has been conducted, though the specific prognostic role of rs2075570 independently requires further study — the incidence and prognosis associations do not always track together in cancer genetics.

Practical Implications

The T allele is the common allele in most populations (52% globally, 80% in East Asians), and carrying one or two copies of T is associated with modestly elevated gastric cancer risk compared to CC homozygotes. The risk is best understood as a population-level susceptibility signal — it does not imply inevitable disease but indicates that normal mucosal defense and barrier genes in the 1q22 region are functioning at a genetically reduced baseline in T carriers. Given the clear gene-environment interaction at this locus, H. pylori infection dramatically amplifies risk for any genetic background at 1q22. Testing for and treating H. pylori remains the highest-yield intervention for T carriers.

The finding that enhanced UBAP2L expression promotes gastric cancer cell proliferation and invasion connects this variant to a druggable axis — UBAP2L inhibition has been shown to suppress gastric cancer cell growth in preclinical models, though no clinical applications exist yet.

Interactions

rs2075570 is in the same 724 kb LD block as rs4072037 (MUC1 synonymous variant, splicing effect) and rs2070803 (MUC1 intergenic variant). While they are correlated, rs4072037 operates through MUC1 alternative splicing — a distinct mechanism from the UBAP2L enhancer pathway tagged by rs2075570. Carriers of risk variants at both rs4072037 and rs2075570 may experience compounding effects on gastric mucosal vulnerability through two independent biological routes: reduced MUC1 mucus barrier effectiveness (rs4072037) and enhanced pro-proliferative gene expression via UBAP2L (rs2075570). H. pylori infection interacts with both pathways and represents the dominant modifiable risk factor.