There’s a genetic condition that prevents the HDL-C cholesterol -in other words, the “good cholesterol”- from clearing and disposing of the “bad cholesterol” which causes an overload of both within the body increasing the risks of a heart disease.
According to a large study in the United States and Europe, elevated levels of good cholesterol might not be good for people. Researchers found a genetic mutation that completely changed the idea that having good cholesterol is always good. This mutation affects the process that the HDL-C performs to clear bad cholesterol from the body and send it to the liver where it is fully eliminated.
This mutation affects a gene called SCARB1 which is the one that helps the body eliminate the bad cholesterol. Researchers said that the mutation actually increases the risks of heart diseases among people genetically predisposed to have high HDL-C levels.
“This is an important study that sheds light on one of the major puzzles relating to cholesterol and heart disease, which is that despite strong evidence showing HDL-C reduces heart disease risk, clinical trials on the effects of HDL-C-raising drugs have been disappointing,” Dr. Peter Weissberg, medical director for the British Heart Foundation, said in a press release. “These new findings suggest that the way in which HDL-C is handled by the body is more important in determining risk of a heart attack than the levels of HDL-C in the blood.”
328 patients, one conclusion
For the study published in the journal Science, the researchers recruited 328 people with high HDL-C, as well as a group with lower levels of it, sequencing the lipid-modifying regions of each of their genomes.
The researchers found a person whose body did not make any SCARB1, explaining his HDL-C levels of nearly three times normal. By generating induced pluripotent stem cells from the person, the researchers created liver cells where they could see the difference between no SCARB1 function, and how it appeared in other participants.
“The work demonstrates that the protective effects of HDL are more dependent upon how it functions than merely how much of it is present,” Dr. Daniel Rader, chair of the genetics department at the University of Pennsylvania, said in a press release.
There still is a lot to learn about the relationship between HDL function and heart disease risk and, eventually, researchers may want to test the genetics of persons with high HDL to make sure they don’t have mutations like this one that raise HDL that do not protect the body against the risk of heart disease or even increase it.