The genetic family ties that bind brothers and sisters
also link their risk for developing clogged
arteries and having potentially fatal heart attacks,
scientists at Johns Hopkins report. And according
to researchers, brothers bear the brunt of the burden.
In a study published in the Nov. 1 edition of the
American Journal of Cardiology, the Johns
Hopkins team found that, regardless of age or lifestyle
factors, if any sibling, brother or sister,
suffers a heart attack, or chest pain from blocked
arteries, the chance of any healthy brothers
developing similar problems rises within 10 years by 20
percent. For sisters, the risk was less but still
evident, at 7 percent.
And, researchers say, the younger the age of the
sibling who first develops heart disease, the
greater the risk that other brothers' and sisters' arteries
will also narrow, harden and clog.
"The risk was greater than previously thought and
makes clear the existence of a substantial, if
uneven, hereditary link in heart disease among brothers and
sisters," said senior study investigator
Diane Becker.
Eventually, she said, a genetic blood test to assess
sibling risk in families with a history of heart
disease could reduce that risk by encouraging earlier
lifestyle and drug interventions.
"In the meantime," she said, "brothers and sisters in
families with a history of heart disease
really need to monitor their health more closely and in
consultation with their physician, and consider
if drug therapy and better diet, exercise and lifestyle
habits are needed."
Becker, a professor at the schools of
Medicine and
Public Health, said
that she and her team of
researchers were most surprised by the very high level of
sibling risk.
Existing statistical risk analyses, such as the
Framingham Risk Score, would not predict so high
a disease risk among men until well into their 80s or 90s,
she said. The Framingham score determines
how likely a person is to suffer fatal or nonfatal coronary
heart disease within 10 years and calculates
risk based on a summary score of such factors as age, sex,
cholesterol levels, blood pressure, diabetes
and smoking.
Study lead investigator Dhananjay "Jay" Vaidya, an
assistant professor in the School of
Medicine, said, "Knowing that your brother or sister had a
heart attack, or that a sibling suffered
chest pain and was rushed to a hospital, stands out as
possibly the most important predictor of
whether or not another sibling develops blocked arteries,
which can lead to a fatal heart attack.
"Genetic factors are clearly to blame," he said,
"although just how that works is unclear."
Vaidya suggests that genes could make these people
more susceptible to known disease risk
factors, or that genes could make people more vulnerable to
some as-yet-unknown risk factor.
In its study, Becker's group used information
collected from 1983 to 2006 as part of a larger
study known as the Sibling and Family Heart Study, which
involves risk-factor monitoring in 800
siblings between the ages of 30 and 60. Study participants
came from nearly 350 families in the
Baltimore region and were generally healthy, but all had at
least one sibling with premature coronary
heart disease that had required hospitalization. Half the
participants were women, and 20 percent
were black.
Blood tests and physical exams were conducted at the
beginning of the study to assess each
individual's risk factors.
Earlier findings by the Johns Hopkins team, in 2005,
showed that people who have a family
history of heart disease needed to keep their weight down.
In these families, siblings who were obese
or overweight had a 60 percent increased risk of suffering
a serious heart ailment, such as a heart
attack, before the age of 60.
As follow-up to their latest findings, Becker said
that she and her colleagues have done a
genomewide scan at deCode Genetics in Reykjavik, Iceland, a
company known for its rapid genetic
study of that country's genetically isolated inhabitants,
to hunt for the genes linked to sibling risk.
"If we can crack this code, then we hope to develop a
blood test for identifying families at risk
long before any symptoms manifest themselves," she said.
Funding was provided by the National Institutes of
Health and the Johns Hopkins Clinical
Research Center. Other Johns Hopkins investigators in this
research were Lisa Yanek, Taryn Moy and
Lewis Becker. Further assistance with results analysis was
provided by Thomas A. Pearson, of the
University of Rochester Medical Center.
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