| More than one in ten American babies come
into the world either too early or too small (or both) and
throughout their lives tend to have health problems that full-term
and average-sized babies do not. Despite extensive research,
the causes of these two conditions, called preterm birth and
fetal growth restriction, are still largely unknown.
Now a group of researchers and clinicians led by Boston University’s
Xiaobin Wang, a School of Medicine associate professor and
an attending pediatrician at Boston Medical Center, is trying
to map the diverse environmental and genetic factors —
and their interactions — that may be involved. The results
“could revolutionize the way clinicians manage those
women and their newborns,” Wang says.
Both conditions are associated with high illness and death
rates in newborns, infants, and children. In addition, Wang
says, “babies born with fetal growth restriction are
more likely as adults to develop cardiovascular disease, diabetes,
hypertension.” At the BU-affiliated Boston Medical Center
(BMC), Wang has found that the patient population is at higher
risk than the national average for these conditions: for instance,
the national average for low birth weight babies is 7.6 percent;
in the BMC population, it’s 12 percent. “If we
understand why they are at high risk,” Wang says, “we
have the potential to bring the national averages down.”
With funding from the March of Dimes Birth Defects Foundation
and the National Institutes of Health, the researchers started
recruiting participants at BMC in late 1998 and now have over
2,400 mother-infant pairs enrolled, making it one of the largest
studies of its kind in the country. To get the necessary data,
Wang’s research team reviews medical records, analyzes
blood samples, and interviews mothers about social and environmental
risk factors.
Take one aspect of this research: the effort to look at the
interaction of genes and environmental risk factors, like
smoking. It’s fairly common knowledge now that women
who smoke during pregnancy have babies with lower birth weights
than women who don’t. Do genetic factors make it likely
that some women’s babies are more adversely affected
than others?
As Wang points out, one person can smoke a pack of cigarettes
a day and be less harmed than another who smokes only one
cigarette a day. “When chemicals from smoking enter
your body, enzymes try to break them down, make them harmless,
and get rid of them,” Wang says. “This capacity
could differ greatly between you and me, because you have
different enzyme activity — and that’s determined
by genes.”
In a study published last year in the Journal of the
American Medical Association, Wang and her colleagues
reported that women who smoked and who had variants of two
specific genes known to be involved with detoxifying cigarette
smoke were at a much greater risk for low birth weight babies
than women who smoke who don’t have those genetic variations.
The findings on the smoking-and-genes interaction are just
a first step, Wang notes. There are many areas where similar
interactions may be equally important.
Her team is on the leading edge of research in this field
and is one of six supported by the March of Dimes Birth Defects
Foundation Perinatal Epidemiology Research Initiatives. “With
a multi-disciplinary team of investigators and our expertises
in clinical medicine, epidemiology, molecular genetics, biostatistics,
and bioinformatics, we have great potential to contribute
to this research field, both in terms of understanding the
causes of preterm birth and fetal growth restriction and of
improving clinical practice and public health intervention,”
Wang says. “It’s a new vision, a new approach
to how we address those issues.”
— Taylor McNeil
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