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UK to extend embryo testing

May 11, 2006 By Claire Ainsworth This article courtesy of Nature News.

Decision allows for screening of genes that do not always cause disease.

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BELFAST - Fertility clinics in Britain should be allowed to conduct tests on test-tube embryos for genetic mutations that do not always result in disease and that manifest later in life, the country's regulatory authority decided on 10 May.

The move means that hopeful parents with some known genetic problems will be able to test their in vitro fertilization (IVF) embryos for genes that can, in some cases, cause certain types of cancer. They can then use such tests to help decide which embryos to implant for their fertility treatment.

The rules over such testing vary greatly from country to country. The United States has no formal regulatory body, and pre-implantation tests are readily available. Whereas in Germany, all pre-implantation testing is banned. The United Kingdom is unique in having an independent regulator that oversees fertility clinics and embryo research.

The guidance only applies to rare mutations in single genes that cause severe diseases. "This is not about opening the door to wholesale genetic testing," the Human Fertilisation and Embryology Authority (HFEA) said in a statement. They have not yet received an application to conduct any such tests, but expect to do so in the near future.

No guarantees

Until now, the United Kingdom has only licensed tests for genes in which carriers are almost guaranteed to develop disease. Such tests are available for diseases including Huntington's, a fatal incurable neurodegenerative condition that strikes adults, or retinoblastoma, an inherited cancer of the retina that develops in at least 90% of young children carrying the faulty gene. Affected infants may need to have their eyes surgically removed.

The general rule was that the same tests should be used on test-tube embryos as in naturally conceived embryos. The HFEA decided to change this; the rules are now different for test-tube embryos than for those already in the womb.

The HFEA was asked to consider the cases of three inherited cancer genes: BRCA1 and BRCA2, which result in an 80% risk of breast cancer, and HNPCC, a form of colon cancer that is also up to 80% penetrant. These conditions tend to strike later in life, when carriers are in their thirties or forties, and are potentially treatable. But even if caught early such cancers are not always curable and preventive measures are invasive and drastic, such as surgically removing the breasts or colon.

Yesterday's decision came after a public discussion and consideration by the HFEA's ethics and law committee. It will act as guidance for the HFEA licence committees, which evaluate applications from individual fertility clinics.

"I think it's a very important decision," says Suzi Leather, chair of the HFEA. She notes that the Authority had received a very wide range of views on the subject from patients and the public. At the meeting, some members of the public praised the Authority's consultation process. Others claimed that the HFEA had exceeded its remit and called for all members to resign.

Case by case

The Authority spent some time debating where to draw the line over which genes should qualify for pre-implantation testing.

They agreed that simply using an arbitrary cutoff for a disease's severity or the likelihood that a gene would cause the disease was unhelpful. Instead, they decided both of these factors should be weighed against each other and considered on a case-by-case basis, at least for an initial period of two years.

"What is serious to one family may not be serious to another," says Christine Patch, an observer from the Human Genetics Commission. "You can't produce a ranked list of conditions from serious to non-serious."

The authority emphasized that the decision would certainly not apply to mild conditions such as eczema and asthma, or diseases caused by multiple genes, such as schizophrenia.

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