CRP is one of the best predictors of cardiovascular events in the blood, and the genetics is the reason we know it is not a cause. Variants that raise CRP for life do not raise heart disease — which is exactly the test a marker has to fail to be demoted from a cause.
C-reactive protein is made by the liver when the body is inflamed. Measured in blood, it predicts cardiovascular events well enough that it is used clinically to refine risk. For years that raised an obvious question: if lowering CRP lowered heart attacks, it would be a drug target worth billions.
You cannot randomise people to a lifetime of high CRP. But genetics did it for us. Some people carry variants that raise their CRP slightly from birth, and they carry them at random with respect to everything else — diet, income, smoking.
So the question becomes answerable. Do the people who inherited higher CRP have more heart disease?
They do not. Repeated analyses using CRP-raising variants as a natural experiment find no matching increase in cardiovascular events. CRP goes up with inflammation, inflammation goes with heart disease, and CRP itself is along for the ride.
This is one of the cleanest examples in human genetics of a marker being separated from a cause, and the method is now standard: if a variant that moves a marker for a lifetime does not move the outcome, the marker is unlikely to be causing it.
The same reasoning has since demoted several other promising targets and confirmed others — LDL cholesterol passes this test, which is part of why lowering it works.
All three come from a meta-analysis of more than 80,000 people — 66,185 in the discovery set across 15 population studies, with replication in 16,540 more. It found 18 genome-wide significant loci, with replication evidence for 8.
The strongest signals for CRP are in CRP itself and in IL6R, the receptor for the cytokine that induces it — neither is in our catalogue yet.
A high CRP measured in blood is worth attention: it means something is inflamed, and the something matters more than the number. Common causes are infection, injury, obesity, smoking and autoimmune disease.
What a high CRP does not tell you is why. And what these variants do not tell you is your CRP — they shift a population average, and a blood test measures the thing directly for a few pounds.
The source. Dehghan et al. (Circulation 2011) meta-analysed genome-wide association data for CRP in 66,185 participants from 15 population-based studies, with replication sought in 16,540 individuals from 10 independent studies — more than 80,000 subjects in total. Eighteen genome-wide significant loci were identified, with replication evidence provided for 8 and confirmation of 7 previously reported loci.
The variants recorded here. rs1183910 (HNF1A), rs6734238 (near the IL1F10/interleukin-1 cluster) and rs13233571 (BCL7B). None is among the strongest CRP signals, which lie in CRP itself and IL6R; those are not currently in this catalogue.
Marker versus cause. Circulating CRP is robustly associated with incident cardiovascular disease in observational cohorts. Mendelian randomisation analyses using CRP-raising alleles as instruments have not found a corresponding increase in coronary risk, which is the basis for the current view that CRP is a marker of inflammatory burden rather than a causal mediator. The contrast with LDL cholesterol, where the same design supports causality, is the reason the method is now routine.
Clinical boundary. High-sensitivity CRP is used in some cardiovascular risk frameworks as an adjunct, measured directly from blood. No guideline uses genotype at these or any other positions to estimate CRP or to modify risk assessment, and nothing on this page is a reason to request a CRP test.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about C-Reactive Protein Levels comes down to these specific, well-studied positions — not a diagnosis.
Because prediction is not causation, and genetics can tell them apart. People who inherit variants that raise their CRP for life do not have correspondingly more heart disease. CRP rises with inflammation; inflammation goes with heart disease; CRP is along for the ride.
No. A blood test measures CRP directly and cheaply, and a measurement beats a prediction every time. These positions shift a population average and say nothing about your level.
That something is inflamed — and what that something is matters far more than the number. Infection, injury, obesity, smoking and autoimmune disease are the common reasons. It is a question for a doctor, not for a genome.
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