Expressive

rs12433177 (SMOC1): Arterial Gene Expression Variant

Key takeaways

  • rs12433177 reduces SMOC1 gene activity across tibial artery, coronary artery, and aorta, as well as esophagus, testis, and tibial nerve
  • The strongest single-tissue effect is in tibial artery, detected at extremely high statistical confidence (p=1.3x10-27) in 953 donors
  • The same variant also reduces SLC8A3 expression in tibial artery, a gene involved in sodium-calcium exchange
  • These are gene-regulation findings, not clinical disease diagnoses
  • No lifestyle or drug-response data is currently linked to this variant in the available evidence

Key takeaways

  • rs12433177 is a regulatory variant near SMOC1 (SPARC-related modular calcium binding protein 1) that consistently reduces SMOC1 gene activity across multiple artery types
  • The strongest effect is in tibial artery, followed by coronary artery and aorta, suggesting a pattern concentrated in vascular tissue
  • The variant also reduces expression of SLC8A3, a gene encoding a sodium-calcium exchanger protein, specifically in tibial artery tissue
  • These are gene-expression findings, not clinical diagnoses - they describe how genes are regulated, not medical outcomes
  • Current evidence is based on eQTL analysis from 953 donors; trait-level GWAS links are not detailed in available source data

What the research says Gene expression data from GTEx v11, drawn from 953 donors using cis-eQTL (short-range gene-regulation) analysis, shows the ALT allele of rs12433177 is associated with reduced SMOC1 expression across seven tissue types, with the largest single-tissue effect in tibial artery (slope -0.48) and additional effects in coronary artery (slope -0.34), aorta (slope -0.32), esophageal muscularis (slope -0.27), esophageal gastroesophageal junction (slope -0.24), testis (slope -0.18), and tibial nerve (slope -0.16) GTEx Portal. A community-based genome-wide association study (GWAS) of 217 plasma metabolites in 2,076 Framingham Heart Study participants identified 31 genetic loci influencing circulating metabolite levels, though the specific contribution of this variant to those findings is not detailed in the available source text. The variant also shows a secondary eQTL effect reducing SLC8A3 expression in tibial artery (slope -0.24) GTEx Portal.

Reported associations

  • SMOC1 expression, tibial artery: ALT allele associated with reduced SMOC1 expression; the largest effect among all tissues tested (slope -0.48, p=1.3x10-27) GTEx Portal
  • SMOC1 expression, coronary artery: ALT allele associated with reduced expression in coronary artery tissue (slope -0.34, p=5.2x10-6) GTEx Portal
  • SMOC1 expression, aorta: ALT allele associated with reduced expression in aortic tissue (slope -0.32, p=3.5x10-9) GTEx Portal
  • SMOC1 expression, esophageal muscularis: ALT allele associated with reduced expression (slope -0.27, p=9.4x10-9) GTEx Portal
  • SMOC1 expression, esophageal gastroesophageal junction: ALT allele associated with reduced expression (slope -0.24, p=5.0x10-5) GTEx Portal
  • SMOC1 expression, testis: ALT allele associated with reduced expression in testicular tissue (slope -0.18, p=2.8x10-10) GTEx Portal
  • SMOC1 expression, tibial nerve: ALT allele associated with reduced expression in tibial nerve tissue (slope -0.16, p=8.2x10-6) GTEx Portal
  • SLC8A3 expression, tibial artery: ALT allele associated with reduced expression of SLC8A3, a sodium-calcium exchanger gene, in tibial artery tissue (slope -0.24, p=8.9x10-7) GTEx Portal

Evidence quality The eQTL evidence for rs12433177 is statistically robust across all seven tested tissues, with p-values ranging from 5.0x10-5 (esophageal gastroesophageal junction) to 1.3x10-27 (tibial artery), all below the standard FDR threshold of 0.05 used in GTEx v11 GTEx Portal. The analysis was conducted in 953 donors. The consistent directional effect (all negative slopes, meaning all reductions in expression) across seven biologically distinct tissues strengthens confidence in the signal. The secondary SLC8A3 eQTL in tibial artery (p=8.9x10-7) is well-supported but is limited to one tissue. No conflicting eQTL findings are present in the provided data. Trait-level associations from the Framingham Heart Study metabolomics GWAS are referenced in the source literature but the specific metabolite linked to this variant, if any, is not detailed in the available text, limiting trait-level conclusions. These findings are preliminary in the sense that eQTL effects describe gene regulation at a population level and have not been translated to clinical endpoints in the provided data.

Tissue-specific expression effects

  • SMOC1: Reduced expression in all three tested artery subtypes (tibial, coronary, and aortic) as well as esophageal muscularis, esophageal gastroesophageal junction, testis, and tibial nerve; the effect is most pronounced in tibial artery GTEx Portal
  • SLC8A3: Reduced expression specifically in tibial artery tissue GTEx Portal

Lifestyle considerations No lifestyle considerations on file for this variant.

Frequently asked questions

What does the SMOC1 gene do?

SMOC1 encodes SPARC-related modular calcium binding protein 1, which plays a role in tissue development and cell signaling. GTEx data shows it is active in arteries, esophageal tissue, testis, and nerve tissue, and its expression in those tissues is influenced by nearby variants like rs12433177.

Which tissues does rs12433177 affect?

Based on GTEx v11 eQTL data from 953 donors, rs12433177 is associated with reduced SMOC1 expression in tibial artery, coronary artery, aorta, esophageal muscularis, esophageal gastroesophageal junction, testis, and tibial nerve. It also reduces SLC8A3 expression in tibial artery.

Is rs12433177 linked to cardiovascular disease?

The available data shows rs12433177 affects gene expression in arterial tissues, but does not establish a direct association with a cardiovascular disease diagnosis. Gene-expression effects describe one step in a biological chain that may or may not translate to clinical outcomes.

What is an eQTL variant?

An eQTL (expression quantitative trait locus) is a genetic variant associated with changes in how much a nearby gene is expressed. rs12433177 is an eQTL for SMOC1, meaning people with its ALT allele tend to have lower SMOC1 activity in certain tissues. This describes gene regulation, not a medical condition.

What is SLC8A3 and why is it associated with this variant?

SLC8A3 encodes a sodium-calcium exchanger protein. GTEx data shows rs12433177 is also linked to reduced SLC8A3 expression in tibial artery, suggesting the variant's regulatory influence extends to at least two nearby genes in that tissue.