New Answers to Miscarriage Found, According to University of Pittsburgh Study

PITTSBURGH, November 8, 2001 — A genetic flaw located in the X chromosome appears to be a key component of recurrent miscarriage among some women, according to a new study.

Reporting in the September issue of the American Journal of Obstetrics and Gynecology, physicians and scientists at the University of Pittsburgh Schools of the Health Sciences and Magee-Womens Research Institute (MWRI) found that an abnormality in one of the mother’s two X chromosomes may be at work in causing repeated pregnancy loss.

“This is exciting news for women who have suffered recurrent miscarriages with no idea why,” said study author W. Allen Hogge, M.D., a professor of obstetrics, gynecology and reproductive sciences and an associate professor of human genetics at the University of Pittsburgh School of Medicine. “Until now, even extensive testing has often been unable to pinpoint a cause.” In fact, up to half of women who have had miscarriages could discover no medical explanation for their losses.

Working with the Children’s National Medical Center at George Washington University, the Pittsburgh team found that the X-chromosome gene flaw is detectable in the mother’s blood. No health risks, however, have been associated with this abnormality in the women themselves.

These women, who are carriers of X-linked recessive disorders, are more likely to miscarry male fetuses, said Dr. Hogge, calling the finding “statistically significant.”

The study of 105 patients revealed that 14 percent of participants with previously unexplained recurrent miscarriages had X-linked recessive lethal traits, continued Dr. Hogge, who is a clinical investigator at Magee-Womens Research Institute and medical director of genetics at Magee-Womens Hospital of the University of Pittsburgh Medical Center.

Some 50 percent of male pregnancies receive the mother’s anomalous X chromosome, causing the fetus to spontaneously abort. Female fetuses are less likely to be miscarried because there are two X chromosomes, and they need only be linked to one. Because of this, they have a 50-50 chance of avoiding the faulty gene.

Though there is no known cure for this genetic flaw, the availability of a blood test will be a significant improvement in risk assessment for future pregnancies, fertility and counseling, said Dr. Hogge.

In addition to Dr. Hogge, other study authors include Mark C. Lanasa, Ph.D.; Carolyn Kubik, M.D; James Harger, M.D.; and Tracy Posen, M.D., all of the University of Pittsburgh School of Medicine; Roberta B. Ness, M.D., MPH, University of Pittsburgh Graduate School of Public Health; Nina Markovic, Ph.D., University of Pittsburgh School of Dental Medicine ; Eric Hoffman, Ph.D., Children’s National Medical Center, and Theodore Nagel, M.D., University of Minnesota.

The study was funded in part by grants from the National Institutes of Health and the NIH Medical Scientist Training Program at the University of Pittsburgh.

Magee-Womens Research Institute, the country’s first research institute devoted to women and infants, was established in 1992 by Magee-Womens Hospital of University of Pittsburgh Medical Center. The University of Pittsburgh School of Medicine’s department of obstetrics, gynecology and reproductive sciences is one of the top three funded NIH departments in the nation.