New embryo test could detect thousands of hereditary disorders

By Rebecca Robey:

UK scientists have developed a new screening technique that could allow prospective parents to test their IVF embryos for any known genetic disease. The test, dubbed ‘a genetic MoT’, would cost just £1500 and could be available by next year pending licensing by the Human Fertilisation and Embryology Authority (HFEA).

There are approximately 15,000 known genetic disorders and currently only two per cent of these can be tested for. The HFEA permits couples to use these tests to screen their IVF embryos prior to implantation in order to avoid having children with debilitating hereditary conditions. Now, researchers at the Bridge Centre in London have developed a new technology called ‘karyomapping’ that they say will be able to detect any genetic disease using a single test.
Conventional genetic screening techniques are limited to searching for the presence of specific genes or gene combinations. Karyomapping, by contrast, examines the embryo’s whole complement of DNA and compares it to those of the parents, grandparents and any siblings. By tracking 300,000 specific genetic markers through the generations, the family’s genetic history can be mapped out and the presence of any genetic regions associated with familial hereditary disorders in the embryo’s DNA can be flagged up.

Professor Alan Handyside, who led the research team, told BBC News Online: ‘the current tests can only identify a small number of defects. One of the main things for patients is that, quite often, there isn’t a test for their particular condition. This is a single test – a universal method’. Karyomapping has been successfully used to screen embryos at the Hammersmith Hospital, London, but the technology is still in the early stages and further evidence will be needed before the HFEA grants a licence for it to be made commercially available. Prof. Handyside said: ‘We are still validating it, but it is going to be a revolution if it works out. It makes genetic screening very much more straightforward’.

Theoretically, the technique could be further applied to determining a predisposition towards many more complicated disorders with genetic elements, such as heart disease, diabetes, breast cancer and Alzheimer’s, or even to detecting other genetic traits such as eye colour. This has led to concern that it could be used for the selection of ‘designer babies’. The researchers, however, refuted this, saying: ‘When you start looking for more than two or three traits, you’ve just got no chance of getting a match. You’d need thousands of embryos, and we don’t have a practical way of making thousands of embryos’. Furthermore, the HFEA will have the authority to specify exactly what the technique can or cannot be used for.