The assisted conception unit at University College Hospital is the United Kingdom’s first clinic to be granted a license to perform pre-implantation genetic diagnosis (PGD) to select embryos that are free of the genetic mutation that leads to familial adenomatous polyposis (FAP). A report in the British Medical Journal notes this marks the first time that doctors in the UK have been allowed to test for a genetic disorder that affects adults and which can be treated. Until now, UK assisted reproduction clinics have been allowed only to screen embryos before implantation for untreatable conditions or conditions that affect children, such as Huntington’s disease and cystic fibrosis. FAP is an autosomal dominant inherited disorder characterized by the presence of hundreds to thousands of adenomatous polyps throughout the colon. All patients with this syndrome develop colon cancer if they are not treated. Because the genetic defect in the germ-line of patients with FAP has been well-characterized, syndromes once thought to be distinct from FAP are now recognized as part of the phenotypic spectrum of FAP. Syndromes with a germline mutation in the adenomatous polyposis coli gene APC include FAP, some Turcot syndrome families, and attenuated adenomatous polyposis coli (AAPC). In the US, estimates of FAP incidence vary from 1 in 6850 to 1 in 31,250. According to Dr. Francis M. Giardielli, Professor of Medicine and Director of Gastroenterology at Johns Hopkins School of Medicine, patients with FAP inevitably develop colon cancer usually in the fifth decade of life, the mean age 39 years old. “In addition, they can have polyps not only in the colon, but these adenomatous polyps can occur in the small intestine, with about 4% of patients developing duodenal cancer.” In addition, says Giardielli, patients may develop “a host of extra-colonic manifestations, including cysts of the skin and osteomas of the bones and other tumors: thyroid cancer, pancreatic, or duodenal cancer. Some patients may have desmoid formation as well, in which they develop fibrous tumors either on the abdominal wall or mesentary, which can obstruct different organs, leading to morbidity and mortality.” While PGD is available through several fertility clinics in the US, Giardielli points out that the high cost for the procedure leaves only one reproductive option for families carrying the FAP mutation: fetal testing with the option of pregnancy termination. Although he says in vitro genetic testing for FAP or cystic fibrosis prior to embryo implantation may be less controversial than subsequent pregnancy termination, Giardielli also notes that some observers have cautioned PGD may be used for other, nonmedical purposes, including gender selection. “One of the issues they’re raising is that once you start down a road of testing embryos for different features and characteristics, it can be become quite expansive,” he says. “So that’s the slippery slope regarding [wider] use of PGD.” For further details, see BMJ 2004;329:1061 (6 November).