CETP Genotype (rs17231506)

HDL cholesterol is often called the "good" cholesterol, and CETP is one of the genes known to shape it. Early genome-wide studies of blood lipids confirmed strong signals at CETP. This test reads one letter, rs17231506, in the stretch of DNA just in front of the CETP gene on chromosome 16. People who carry the T version tend to have somewhat higher HDL cholesterol than people with the more common C version.

That sounds like good news, and in a narrow sense it is. But one of the big lessons of heart research over the past two decades is that a higher HDL number does not automatically mean a healthier heart. This page explains what the variant does, what the large studies found, and why your LDL cholesterol and apoB are the numbers that guide heart prevention, not this result.

What CETP Does

CETP (cholesteryl ester transfer protein) is a protein in your blood that moves cholesterol out of HDL particles and into LDL-type particles, the ones that carry apolipoprotein B (apoB), swapping triglycerides back the other way. When CETP is less active, more cholesterol stays in HDL. HDL cholesterol goes up, and LDL cholesterol tends to come down slightly. People born with lower CETP activity show exactly that pattern.

What This Variant Actually Does

rs17231506 does not change the CETP protein itself. It sits in the gene's promoter region, the stretch of DNA that helps control how much CETP is made, which is why it is called an upstream variant.

In European samples from the 1000 Genomes Project, the T version is inherited together every time with a neighbouring upstream variant, rs247616. A 2012 study of 56 human livers found that variants in this upstream stretch, led by rs247616, were linked to how much CETP message each gene copy makes. A 2015 lab test in liver cells found rs247616 lowered CETP output about 1.7-fold. Another linked variant raised it in the same test, but the authors concluded that this stretch of DNA goes with lower CETP output across tissues. The same study found no clear effect of rs17231506 on its own in liver cells. So in people of European or East Asian ancestry, rs17231506 is best read as a marker of an inherited stretch of DNA that turns CETP down, rather than the letter doing the work itself.

How Much It Affects CETP and HDL

Most of the detailed CETP measurements come from older, partly linked markers. A 2008 meta-analysis of 92 studies and 113,833 healthy people looked at TaqIB (rs708272) and two other common CETP variants. For each copy of the HDL-raising TaqIB version, CETP mass in the blood was about 10 percent lower, CETP activity about 9 percent lower, and HDL cholesterol about 4.5 percent higher. The other two variants showed a very similar pattern. In a US study of 18,245 women, each copy of the HDL-raising TaqIB version added about 3.1 mg/dL of HDL.

rs17231506 itself has been tied to higher HDL in very large genetic studies, including a 2021 analysis of about 1.65 million people from several ancestries, which also linked T to slightly lower triglycerides. Because rs17231506 and TaqIB are only partly linked, the TaqIB figures are a guide to the size of the effect, not an exact measure for this letter. These studies estimated the effect per copy, assuming each copy adds a similar amount, so two copies (T/T) would be expected to give roughly double the nudge of one.

Heart Disease: What the Genetic Studies Show

Several large studies suggest that being born with somewhat lower CETP activity goes with a somewhat lower chance of heart disease, but the effect is small. In the 2008 meta-analysis, which included 27,196 people with coronary disease and 55,338 without, each HDL-raising TaqIB copy carried about 5 percent lower odds of coronary disease. The authors described this as a weak link, about what you would expect from the small rise in HDL.

Other studies point the same way. In the US women's study, each TaqIB copy was linked to 24 percent lower risk of heart attack, though that estimate rests on only 198 heart attacks. In the Copenhagen City Heart Study of 10,261 people followed for up to 34 years, people carrying four HDL-raising versions across two CETP variants, compared with none, had up to 14 percent higher HDL, slightly lower LDL, and a lower risk of ischemic heart disease (hazard ratio 0.74) and of death from any cause (0.88). And in a 2017 study of 58,469 people, the roughly 1 in 975 who carried a rare variant that switches off one copy of CETP had HDL about 22.6 mg/dL higher, LDL about 12.2 mg/dL lower, and 30 percent lower odds of coronary heart disease.

Why Higher HDL Is Not the Whole Story

If higher HDL protected the heart directly, every gene change that raises HDL should lower risk. It does not. A 2012 Mendelian randomisation study, which uses inherited variants as a natural experiment, found that an HDL-raising variant in a different gene, LIPG, did not lower heart-attack risk, and neither did a score built from 14 variants that raise HDL alone. The authors said this challenges the idea that raising HDL will uniformly lower heart-attack risk.

A 2017 study of 102,837 people then asked where the benefit of CETP variants comes from. A CETP genetic score was linked to higher HDL, lower LDL and apoB, and a modestly lower risk of cardiovascular events (odds ratio 0.946). The size of that benefit matched the fall in apoB, the protein on LDL-type particles. When the CETP score was combined with variants that mimic a statin, the apoB drop shrank and so did the benefit. The likely lesson: what helps is having fewer LDL-type particles, not having more HDL.

Very high HDL is not always reassuring either. In two Copenhagen studies of 116,508 people, the link between HDL and death from any cause was U-shaped, with extremely high HDL linked to higher mortality. This was an observational finding that the authors said needs confirming, but it is one more reason not to treat a high HDL number as a free pass.

What the CETP-Inhibitor Trials Showed

Drug makers tried to copy the CETP-variant effect with medicines that block CETP. Four large outcome trials tested them:

• Torcetrapib (2007, 15,067 people): HDL rose 72 percent and LDL fell 25 percent, yet cardiovascular events rose 25 percent and deaths rose 58 percent. The drug also raised blood pressure, an off-target effect, though the investigators could not rule out harm from CETP blocking itself.
• Dalcetrapib (2012, 15,871 people after a recent heart event): HDL rose 31 to 40 percent with little change in LDL, and there was no reduction in repeat cardiovascular events.
• Evacetrapib (2017, 12,092 people): HDL more than doubled (up 133 percent) and LDL fell 31 percent, but events were unchanged: 12.9 percent on the drug versus 12.8 percent on placebo.
• Anacetrapib (2017, 30,449 people already on a strong statin): HDL roughly doubled and non-HDL cholesterol fell 18 percent. Over about four years, major coronary events fell from 11.8 to 10.8 percent, a modest 9 percent relative reduction.

Huge rises in HDL did not reliably prevent heart events. Torcetrapib and evacetrapib also lowered LDL cholesterol, by a quarter to a third, but did not help: torcetrapib had off-target harms, and the evacetrapib trial was stopped early, after about two years, for lack of benefit. The 2019 European guidelines noted that in the evacetrapib and anacetrapib trials, HDL more than doubled but risk did not appear to fall beyond what the modest drop in apoB would predict, which fits the genetic evidence that apoB is what matters. A newer CETP inhibitor, obicetrapib, is being tested in an outcome trial called PREVAIL (ClinicalTrials.gov NCT05202509), which was still ongoing as of October 2026. The same European guidelines found no randomized-trial evidence that raising HDL with drugs lowers cardiovascular events, and set no treatment target for HDL. The 2026 US cholesterol guideline from the American College of Cardiology and American Heart Association sets its treatment goals for LDL cholesterol and non-HDL cholesterol.

A Note on Eye Health

One other link is worth knowing about. In a pooled analysis of 30,953 Europeans aged 50 or older, higher HDL was associated with a somewhat higher chance of age-related macular degeneration (AMD), an eye condition of later life, and the CETP variant tied to AMD in genetic studies was rs17231506, in the HDL-raising direction. This is an association, not proof of cause, and it does not change routine eye care: regular eye checks as you get older are sensible whatever your genotype.

How It Relates to TaqIB and rs3764261

Variants that tend to be inherited together are described as being in linkage disequilibrium. In 1000 Genomes samples of European (CEU) and Han Chinese (CHB) ancestry, rs17231506 and rs3764261, another CETP promoter variant, are inherited together every time, so results for one apply to the other. The link with older markers is looser: in European samples about half the variation is shared with TaqIB (rs708272) and with -629C>A (rs1800775), and the HDL-raising TaqIB version usually travels with T. In Yoruba samples from West Africa the links are much weaker, so in people of African ancestry these variants can give different results and each should be read on its own.

How Common It Is

In the gnomAD v4.1 genome data, about 26 percent of all gene copies carry T. It is about 32 percent in people of non-Finnish European ancestry, which works out to roughly half carrying at least one copy and about 1 in 10 carrying two. It is similar in people of South Asian ancestry (about 34 percent) and Latin American ancestry (about 27 percent), and less common in people of East Asian (about 17 percent) and African ancestry (about 14 percent).

How Results Are Reported

This result is the pair of letters at position 16:g.56960616 on the current GRCh38 reference genome (position 56994528 on the older GRCh37 build), read on the forward strand of chromosome 16, the same strand the CETP gene is read from. C is the more common version and T is the HDL-raising version. C/C means no copies, C/T or T/C means one copy (the order does not matter), and T/T means two.

This variant is best described as an association: it is statistically linked to a trait, here higher HDL cholesterol, in large population studies. It is not a disease-causing change, and ClinVar, the US public database of variant classifications, has no clinical entry for it.

Why You Only Need This Test Once

Your DNA does not change, so your rs17231506 genotype at 25 will be the same at 65. What changes over time, and what is worth tracking, is your blood lipids: LDL cholesterol, apoB, HDL cholesterol and triglycerides.

What to Do With Your Result

Whatever your genotype, the practical steps are the same:

• Know your LDL cholesterol and apoB: in the genetic studies, the heart benefit linked to lower CETP activity tracked the fall in apoB, not the rise in HDL.
• Do not treat a high HDL as a free pass: HDL raised by CETP variants or drugs has not translated simply into lower heart risk, and very high HDL was linked to higher mortality in one large observational study.
• Do not chase a higher HDL number: European guidelines set no HDL target and find no trial evidence that raising HDL with drugs prevents heart events, and the 2026 US guideline sets its goals for LDL and non-HDL cholesterol.
• Talk with your clinician about your overall risk: blood pressure, smoking, blood sugar, family history and your lipid results are what shape prevention decisions, not this genotype.

Carrying T is common and tends to lift HDL a little. It is an interesting piece of your lipid genetics, but your blood tests, not this letter, are what guide care.