WEDNESDAY, Aug. 23 (HealthDay News) -- New studies have found a genetic component to two health problems in blacks: premature birth and prostate cancer.

The findings buttress previous research linking genetics to health problems in different racial and ethnic groups.

In the case of premature birth and prostate cancer, knowing the increased risk may lead to new treatments, the researchers said. The findings were published in this week's edition of the Proceedings of the National Academy of Sciences.

In the first report, researchers pinpointed a gene that appears to be involved in the significantly increased risk of premature birth among black women. The researchers found that a variation in the SERPINH1 gene heightens the risk of an early break in the amniotic sac, resulting in premature delivery.

"We were interested in finding genetic contributors to preterm birth in African-Americans, because they have a substantially higher risk of delivering a preterm baby than non-black individuals," said lead researcher Dr. Jerome F. Strauss III, dean of Virginia Commonwealth University's School of Medicine.

"There are genetic factors that might predispose the 'bag of waters' to break early and result in a preterm birth," Strauss said.

In the study, Strauss and his colleagues studied this gene variation, called the minor "T" allele polymorphism, which is a marker of African ancestry. They found that this polymorphism leads to decreased levels of a protein that stabilizes collagen, which is needed to strengthen the membrane that contains the fluids that surround the fetus.

"The strength of that bag is determined by the amount of collagen," Strauss said.

In two studies, Strauss' team showed that this gene polymorphism was almost three times more common in premature babies born to black women. "This points a finger at this gene as a contributor, a risk factor for pregnancies that will result in a preterm delivery," Strauss said. "This could contribute to more than 12 percent of preterm deliveries in African-American women."

Strauss thinks screening could identify those women at risk for premature delivery. In addition, he thinks there are ways to increase the amount of collagen that is produced.

"Just because you are carrying around a bad gene doesn't mean 100 percent of the time you are going to end up with a bad outcome," Strauss said. "There are environmental factors that determine whether the gene actually causes the bad effect."

For instance, vitamin C is needed to make collagen, Strauss said. "If you could identify people at risk, you could make sure they had enough vitamin C early on and throughout pregnancy," he said. "Interventions that reduce risk factors are, hopefully, going to be beneficial to people who carry the genetic risk factor."

In the second study, researchers found that a part of chromosome 8 is linked to an increased risk of prostate cancer in black men, who have about 1.6 times greater risk of developing the disease than white men. Part of this increased risk is probably due to genetic factors, the researchers said.

"It appears that we found a genetic risk that predisposes to prostate cancer in the general population, but particularly in African-American men," said lead author Dr. Matthew L. Freedman, an instructor at Harvard Medical School. "This is one of the first times that a genetic risk factor for prostate cancer has been found and confirmed in the general population."

In the study, Freedman's team looked for genetic factors associated with prostate cancer in 1,597 black men who had the disease. The researchers found that a region of chromosome 8, called 8q24, increased prostate cancer risk in men of African ancestry.

This increased risk was greater in men diagnosed with prostate cancer before the age of 72, which fits with data that show that prostate-cancer risk decreases with age in black men.

DeCODE, an Icelandic company that does gene research, found the same genetic link to prostate cancer among Icelandic men, and in fact, replicated their results in a number of independent populations, Freedman noted.

Freedman believes this finding could be used to screen those at risk for prostate cancer. There are three factors that are used to determine prostate cancer risk: age, family history and ethnicity, he said. "To my mind, this serves as the fourth risk factor, because it has been replicated in diverse populations," he added.

More information

The National Center for Biotechnology Information can tell you more about genes and disease.