Good cholesterol can also be bad
for you!
It turns out what’s referred to as ‘good’ cholesterol
might actually put you at a much greater risk of heart disease. 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
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.
Senior author Daniel J. Rader said that the 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. Rader suggests that a therapeutic
approach to increase the expression or activity of SCARB1 could be a new way to
reduce the risk of heart disease even though it would reduce HDL blood levels.
He added, ‘The work demonstrates that the protective
effects of HDL are more dependent upon how it functions than merely how much of
it is present,’ Rader concluded. ‘We still have a lot to learn about the relationship
between HDL function and heart disease risk.’
Their findings are published in Science.
Source: www.thehealthsite.com
14.03.2016
If a man does
his best, what else is there?
George
S. Patton
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