Discovery
Of 'Heart Attack Gene' Adds Insight Into Risk Factors
Healthy Lifestyle
Still Recommended
A gene linked
to coronary heart disease in humans recently was discovered
by researchers and reported in the journal Science.
Now that scientists
have identified the first gene mutation responsible for
heart attacks, physicians eventually will be able to use
this additional tool to help determine a patient's
risk for heart disease.
Although the mutation
has only been isolated in one family with roots in Iowa, the
finding may shed light on the genetic pathways involved in early
coronary artery disease and heart attacks, researchers say.
It also offers a new
risk factor to consider, and a way to decide who needs to be
extra vigilant about heart health.
"Until we have gene
therapy, we are left with getting more aggressive with risk
factors, isolating who is at higher risk and trying to
change the course of the disease," says Dr. Daniel Fisher, a
clinical assistant professor of medicine at New York University
School of Medicine. "This is just something else that we're
going to say let's get more aggressive."
The role of genetics
in coronary disease is difficult to untangle because it is a
considered a late-onset disease, experts say.
"By the time you find
somebody, the parents have already died and the children are
too young to have had the disease, which is critical to being
able to do the work," says Dr. Eric J. Topol, senior author
of the new study and chairman of the department of cardiovascular
medicine at the Cleveland Clinic.
Experts
Look for Risk Factors
The study started
when Dr. Topol met with a heart attack patient at the Cleveland
Clinic. During that first consultation, the man explained that
he had 10 siblings, nine of whom had had heart attacks.
"That was a pretty
strong signal" that there was a genetic link, Dr. Topol says.
Despite the high incidence
of heart attacks in the family, none of its members had high
cholesterol levels, which are extremely common in heart attack
patients.
"Most people who have
a heart attack have abnormal cholesterol, so it had to be something
more penetrating and important than cholesterol to explain the
disease," Dr. Topol says.
"It" turned out to
be cracks in an arterial wall.
When the researchers
did a genetic analysis of 13 family members (nine of whom had
had a heart attack), they identified a region on chromosome
15 that includes a gene thought to be involved in blood vessel
development.
The researchers discovered
that family members with heart disease all carried a mutated
version of the gene MEF2A. Those without the disease did not have
the mutation.
The mutated version
of the gene MEF2A "at birth sets up an artery wall that is not
intact and then predisposes the person to a heart attack," Dr.
Topol explains.
"It's a 100 percent
risk," Dr. Topol says. "It's a pre-committed path to a
heart attack." The heart attack usually occurs in men age 45
and over and in women age 50 and over.
Healthy
Lifestyle May Stall Risk from Gene
What researchers do not yet
know is how important environment factors are in relationship
with a genetic mutation.
Experts are interested
in knowing if altering environmental factors could
stave off a heart attack in those with the genetic mutation.
"We know there is
a defect in the artery wall, and if someone doesn't have the
risk factors, they may still get this disease but it should
be deferred substantially" by pursuing a healthy lifestyle,
Dr. Topol says. "It is pretty unlikely that they could ward
it off completely."
Since that first family
member arrived in Dr. Topol's examining room, some 250 family
members have been studied and given their genetic information.
And the number keeps growing.
Having this information
"changes everything," Dr. Topol says. "Now to be told you do
or don't have this gene is a whole different story. It's much
more definitive.
"If you do have this
gene, many have a long way to go to turn around that risk,"
Dr. Topol explains. "And in the ones who don't have the
gene, it's a tremendous amount of mental relief."
"Hopefully this [heart
attack risk] can be changed at the earliest age," Dr. Topol
says. "This is a disease that takes at least 20 to 30 years
to incubate, so if you can start early, it's remarkable how
much you can do."
Always consult your
physician for more information.
|
January 2004
Discovery
Of 'Heart Attack Gene' Adds Insight Into Risk Factors
Experts
Look for Risk Factors
Healthy
Lifestyle May Stall Risk from Gene
Tissue-engineered
Valves Give Diseased Hearts New Life
Online
Resources
Tissue-engineered
Valves Give Diseased Hearts New Life
Heart valves engineered
from patients’ own tissue may offer a new treatment for
valvular heart disease, according to a press statement from
researchers at the American Heart Association’s
Scientific Sessions.
“Using this
tissue-engineered valve overcomes many of the problems with
mechanical or donor valves because it is a living structure
from the patient’s own tissue, and so it does not cause
an immunological reaction,” says Dr. Pascal M. Dohmen,
head of tissue engineering research and staff surgeon of the
department of cardiovascular surgery at Charité Hospital
in Berlin, Germany.
Dr. Dohmen and colleagues
presented data on the first 23 patients to receive tissue-engineered
pulmonary valves in the heart, a procedure still considered
experimental.
The patients, whose
average age was 44, had aortic valve disease. The aortic
valve connects the heart’s left ventricle with the aorta,
the main artery that distributes blood throughout the body. A
diseased valve may either open or close improperly, and pressure
can build in the ventricle, injuring the heart.
Physicians can
treat the condition with medications or by surgically replacing
the patient’s aortic valve with a donor valve, a mechanical
valve, or the patient’s pulmonary valve. The pulmonary
valve is between the right ventricle and the pulmonary artery.
In a surgical “swap”
called the Ross procedure, the abnormal aortic valve is replaced
with the pulmonary valve, and the pulmonary valve is replaced
with a donor valve.
Dr. Dohmen engineered
a new pulmonary valve from the patients’ own cells. The
surgical team implanted the patients’ healthy pulmonary
valve into the aortic position. Then the tissue-engineered
valve was implanted in the right ventricular outflow tract,
where the pulmonary valve originally was.
With up to three years
of follow-up, the engineered valve’s performance was “excellent,”
Dr. Dohmen reports.
Echocardiography showed
that the valves were functioning normally; the valve leaflets
or flaps appeared smooth and pliable, and showed no signs of
calcification.
Always consult your
physician for more information.
Online
Resources
(Our Organization
is not responsible for the content of Internet sites.)
American
Heart Association
Centers
for Disease Control and Prevention (CDC)
HealthierUS.Gov
National
Heart, Lung, and Blood Institute (NHLBI)
National
Institutes of Health (NIH)
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