A genetic variant in black women increases the risk of preterm premature rupture of membranes (PPROM) - a leading cause of preterm birth
"This is probably the most convincing study to date that specific, fairly common, genetic variants will increase risk," said Nancy Green, MD, medical director of the March of Dimes.
In addition to helping explain why black women in the United States are nearly twice as likely to have a baby born prematurely as white women, the new findings could help physicians identify those women who are at risk and guide researchers in developing therapeutic interventions.
A number of factors are associated with an increased risk of preterm birth, including smoking, a history of preterm delivery, infection, and low body mass index. But about half of the cases have no known cause, and researchers have been searching the human genome for genes that may increase a woman's likelihood of preterm delivery.
This latest study has identified a possible culprit: a variant in a region of the SERPINH1 gene that codes for a protein called heat shock protein 47 (Hsp47). Heat shock protein 47 stabilizes collagen and gives strength to the amnion. Presence of the variant leads to decreased production of Hsp47 and weakened amnionic membranes that are more likely to rupture prematurely and lead to preterm birth. The genetic polymorphism is present in approximately 12.4% of black women compared with 4.1% of white women.
In 2 separate case-control studies involving 244 black women experiencing PPROM and 358 matched controls, the investigators found that the genetic variant occurred almost 3 times more frequently in neonates born from pregnancies complicated by PPROM than in controls. The findings suggest that the genetic variant is responsible for approximately 12% of preterm births. "So it's not the major cause," said principal investigator Jerome Strauss III, MD, PhD, dean of Virginia Commonwealth University's School of Medicine, in Richmond. "It's one cause and it is a beginning," he noted.
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