The Upside and Downside of Screening Embryos
Oct. 21, 2009— -- Genetic screening of embryos, sperm and eggs has been tied to the worst aspects of eugenics, but a new case study in one of the nation's leading medical journals shows some benefits may come from genetic analysis of donors.
The study documents the case of a then-23-year-old sperm donor whose donations in 1990 and 1991 led to the birth of 22 known children. Recently, however, it has also been discovered through gene testing that he has hypertrophic cardiomyopathy (HCM), a genetic heart condition that can lead to heart failure and sudden death, among other problems, and a problem some of his children now also have.
"This is the first time a genetic disease has been documented this way," said Dr. Barry Maron, a cardiologist with the Minnesota Heart Institute Foundation. "It's supposed to make the point that this is an invisible risk. Could it happen again? Of course. That's the point of the whole exercise."
While the FDA requires sperm donors to be screened for multiple conditions, these tests are aimed at preventing the transmission of infectious diseases such as AIDs, and largely do not address genetically transmitted diseases like the genetic heart defect that afflicted this sperm donor's offspring.
The current FDA regulations require the testing for genetic diseases like cystic fibrosis, sickle cell anemia, and Tay-Sach's, but genetic heart problems are not included in the screening.
"The FDA had not paid much attention to the transmission of genetic diseases," Maron said. "The emphasis has been on transmission of infectious diseases."
The anonymous sperm donor's screening did not pick up his heart condition, and of his 24 children (two from his wife, the rest from donation), nine have the genetic mutation responsible for HCM. One has functional limitations, chest pain and fatigue because of this problem; another has palpitations; and one died of progressive heart failure at the age of 2, while awaiting a transplant.
The case study appears in the newest issue of the Journal of the American Medical Association.
In a related editorial in the journal, Judith Daar of Whittier Law School in Costa Mesa, Calif., and Dr. Robert Brzyski of the University of Texas Health Science Center at San Antonio say the study shows the need for increased gene screening and counseling, although they note that this is not foolproof when it comes to the health of potential offspring.
"Geneticists caution, however, that prospective parents should be counseled about the limitations of genetic testing and its relationship to long-term offspring health," they wrote. "Providing recipients a clean genetic bill of health about a chosen donor can lead to a false sense of confidence about the risk of illness their child might face. A significant proportion of some genetic conditions ... arise from [new] mutations."
