Penn Study Shows a Form of Genetically Elevated “Good” Cholesterol May Actually be Bad [News release]

From the 10 March 2016 Penn Medicine news release

 

Research has implications for better understanding the relationship between “good” cholesterol function – in addition to level — and heart disease risk

PHILADELPHIA – The generally accepted medical maxim that elevated HDL cholesterol (HDL-C) is “good” has been overturned by a multi-center, international study, led by researchers from the Perelman School of Medicine at the University of Pennsylvania. They show that a certain genetic cause of increased HDL-C may actually be “bad,” noting that a specific mutation in a gene which encodes a cell receptor protein that binds to HDL prevents the receptor from functioning. The mutation causes an increased risk of coronary heart disease even in the presence of elevated levels of HDL-C or “good” cholesterol. Their findings are published this week in Science.

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HDL, or ‘good’ cholesterol, can remove cholesterol from arteries and shuttle it to the liver where it is eliminated, but this process can be disrupted in certain circumstances (such as deficiency of SCARB1).

Credit: The lab of Daniel Rader, MD, Perelman School of Medicine, University of Pennsylvania

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Previous research raised the possibility that HDL might not be quite as protective against heart disease as generally believed by cardiologists, especially after several clinical trials of HDL-raising drugs showed little or no effect. “The thinking about HDL has evolved recently to the concept that it may not directly protect against all heart disease,” said senior author Daniel J. Rader, MD, chair of the department of Genetics.  “Our results indicate that some causes of raised HDL actually increase risk for heart disease. This is the first demonstration of a genetic mutation that raises HDL but increases risk of heart disease.”

Rader and his colleagues sequenced the lipid-modifying regions of the genomes of 328 people with markedly elevated HDL (along with a control group with lower HDL) to identify genetic causes of high HDL. One of the genes they focused on was SCARB1, which encodes for Scavenger Receptor B1 (SR-B1), the major receptor for HDL on cell surfaces.

In the course of this sequencing, they identified, for the first time, a person without any SCARB1 function, typified by an extremely high HDL-C level of about 150 mg/dL, whereas the normal level is about 50 mg/dL. The subject had two copies of a SCARB1 mutation called P376L, which the team showed caused a breakdown in HDL receptor function.

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Measuring HDL Particles as Opposed to HDL Cholesterol Is a a Better Indicator of Coronary Heart Disease, Study Suggests

English: HDL (Photo credit: Wikipedia)

 From the 11 July 2012 ScienceNewsDaily article

Until recently, it seemed well-established that high-density lipoprotein (HDL) is the “good cholesterol.” However there are many unanswered questions on whether raising someone’s HDL can prevent coronary heart disease, and on whether or not HDL still matters. A team of researchers at Brigham and Women’s Hospital (BWH), the University of Pittsburgh Graduate School of Public Health (GSPH) and other institutions, have discovered that measuring HDL particles (HDL-P) as opposed to HDL cholesterol (HDL-C) is a much better indicator of coronary heart disease (CHD), and that HDL does indeed, still matter.

Related articles

• Some ‘good’ cholesterol unable to protect heart (news.bioscholar.com)
• Some “Good” Cholesterol May Be Bad For Heart (medicalnewstoday.com)
• Some HDL, or ‘good’ cholesterol, may not protect against heart disease (eurekalert.org)
• The Cholesterol-Heart Disease Connection (everydayhealth.com)
• Will high HDL level lower the risk of heart attack? (thehindu.com)
• Algae Extract Increases Good Cholesterol Levels, WSU Researcher Finds (detroit.cbslocal.com)
• How To Raise HDL Cholesterol (answers.com)
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• High-density lipoprotein still matters, look at the particles! (eurekalert.org)

Some “Good” Cholesterol May Be Bad For Heart

Fr0m the 20 May 2012 article at Medical News Today

It appears that in some cases, high-density lipoprotein (HDL) cholesterol, the so-called “good” cholesterol, does not protect againstheart disease, and may even be harmful. A new study suggests a subclass of HDL that carries a particular protein is bad for the heart.

Previous studies have shown that high levels of HDL cholesterol are strongly linked to low risk of heart disease. But trials where people have been given drugs to increase their levels of HDL cholesterol have yielded inconsistent results: leading to the idea that HDL cholesterol may actually have protective and non-protective elements.

Now, researchers at the Harvard School of Public Health (HSPH) have found that when the surface of HDL cholesterol bears a small protein called apolipoprotein C-III (apoC-III), there is an increase in the risk of heart disease, and when it is absent, HDL cholesterol is especially heart protective….

Related articles

• HDL ‘Good Cholesterol’ Found Not to Cut Heart Risk – NYTimes.com (policyabcs.wordpress.com)
• ‘Good’ cholesterol’s heart benefits challenged (cbc.ca)
• Some ‘good’ cholesterol unable to protect heart (news.bioscholar.com)
• Will high HDL level lower the risk of heart attack? (thehindu.com)
• Some HDL, or ‘good’ cholesterol, may not protect against heart disease (eurekalert.org)
• “Good” HDL Cholesterol May Not Protect Heart After All, Study Suggests (wibw.com)
• HDL Won’t Protect Against Heart Disease, Says Study Proving ‘Good’ Cholesterol Is Wishful Thinking (blisstree.com)
• HDL ‘Good Cholesterol’ Found Not to Cut Heart Risk – NYTimes.com (fitnessgroan.me)
• ‘Good’ cholesterol doctrine may be flawed: study (news.yahoo.com)