As more families opt for pre-implantation genetic diagnosis to screen embryos for inherited diseases, determining the regulatory and ethical guidelines to govern such screenings is “proving difficult,” the Chicago Tribune reports. Although the field of embryonic testing initially focused on identifying genetic defects that are certain to cause suffering or death early in life, it has broadened to include tests for genes linked to breast and ovarian cancer, which are not always fatal, occur later in life and affect 50% to 85% of those who carry the gene, according to the Tribune. The leading U.S. genetic diagnosis clinic, which is the largest in the world, conducted more than 1,800 screenings in 2008 “aimed at weeding out embryos that carried worrisome family conditions, from sickle cell anemia to cystic fibrosis,” the Tribune reports. Different countries vary in their regulation of PGD. In the U.S., doctors are allowed to select embryos for a particular sex, a practice that is not allowed in Great Britain, where each instance of PGD must be registered with the British Human Fertilization and Embryology Authority. BFEA has approved the use of PGD for about 70 genetic defects “after intensive public consultation about what is a serious enough problem to justify trying to eliminate it,” the Tribune reports. It is “significantly easier” to conduct PGD in the U.S. because the government only licenses clinics, not individual procedures, the Tribune reports. Mark Hughes, director of the Detroit-based Genesis Genetics Institute, said his company has tested for 171 genetic defects. In the U.S., “there is no approval mechanism,” Hughes said, adding, “No one is saying you can do this to save a sibling but you can’t do this for BRCA1,” a gene linked to breast cancer. According to a John Hopkins University study, nearly 40% of individuals surveyed believed that embryo screening should be regulated more closely for ethical reasons. An additional 19% said the screening should be banned altogether, for reasons ranging from the belief that discarding an embryo is immoral to concerns that selecting against certain diseases will devalue the lives of people already living with those conditions. Clare Williams, a bioethics specialist at Kings College London, said that during public hearings in Britain, “quite a lot of people felt there could well be treatment (for some conditions) by the time these children grow up, and then (their condition) won’t be an issue.” Some experts say it would be beneficial to place limits on the type of genetic defects doctors are allowed to screen for in the U.S., the Tribune reports. The Hopkins study found that, as of 2006, 65% of about 200 U.S. clinics offering embryo screenings allowed clients to choose the gender of the implanted embryo, regardless of the gender of existing children or whether the child was their first. The Tribune reports that such data and a California-based genetics lab’s recent announcement that it would be able to select eye and hair color have raised public concerns about genetic selection of embryos. The lab’s claims have been “disproved,” and many experts believe that expanded embryo screening “probably is not a slippery slope toward designer babies” because PGD is “costly and difficult,” there are a limited number of embryos to choose from and “finding one that includes a number of desired traits would be very difficult,” the Tribune reports. Hughes said the “things you might want to select for in a child — intelligence, athletic prowess, body stature — involve not single genes but many, many genes.” According to the Tribune, PGD, used in conjunction with in vitro fertilization, costs about $3,500 in the U.S. and twice that in Britain (Goering, Chicago Tribune, 3/25).