Task Force Releases Guidelines on Advising First Cousin Couples Regarding Genetic Defects

SEATTLE, WA -- April 3, 2002 -- After more than two years of research, a task force funded by the National Society of Genetic Counselors and made up of genetic counselors, physicians, and epidemiologists centered at the University of Washington, announce the first comprehensive set of guidelines for consanguineous couples, such as first cousins, who are contemplating having children.

Just published in the current issue of the Journal of Genetic Counseling, the guidelines provide recommendations to physicians and genetic counselors on counseling and advising these couples.
To develop the recommendations, the authors completed a significant literature review of all studies published in English in the medical literature, and some additional materials.

The article was developed by a task force headed up by lead author Robin Bennett, president-elect of the National Society of Genetic Counselors and senior author Dr. Arno Motulsky, professor emeritus (active) of Medicine and Genome Sciences at the University of Washington and a pioneer in medical genetic studies.

"Because of widespread misconceptions about the actual level of risk to offspring, some of these pregnancies are terminated and couples suffer a lot of needless anxiety," said Dr. Bennett. "Cousins concerned about a pregnancy arising from their union have often found it difficult to get accurate information about risks to their offspring oftentimes because of social stigma or laws prohibiting marriage between first cousins in 30 states."

The authors estimate the additional risk amongst consanguineous couples above the base (general population) risk for significant birth defects including mental retardation or genetic disorders, is from 1.7-2.8% for first cousin unions. From her experience in genetic counseling at the University of Washington Medical Center, Dr. Bennett believes these numbers are far lower than most people's perception of the risks.

The consensus of the task force concludes that beyond a thorough medical family history with follow-up of significant findings, no additional preconception screening is recommended for consanguineous couples.

The couples should be offered thorough genetic screening tests that would routinely be offered to other couples of their ethnic group.

"These recommendations become even more important as healthcare practitioners are seeing more cousin unions in the immigrant population coming to North America from Africa and the Middle East," elaborates Dr. Bennett. "In some of these societies, the authors note, cousin marriages are actually traditionally preferred and quite common -- as high as 60% of unions."

Better information and appropriate guidelines are especially needed by physicians and genetic counselors who work with these groups so that more objective and culturally respectful services can be provided.

The paper also includes guidelines for screening for the recessive genes that can produce offspring with disorders of metabolism or hearing, among others. In many cases, these disorders can be treated if found early in life. In the same vein, the importance of routine, regular early childhood pediatric care, as set out in American Academy of Pediatrics guidelines, is emphasized for children of cousin unions.

The authors also note that laws concerning consanguineous couples may eventually change as a result of evidence about actual risks.

SOURCE: National Society of Genetic Counselors