A universal genetic test for embryos that can screen for almost any inherited disease is to be offered to prospective parents within months, after research demonstrated its effectiveness for the first time.

British doctors will apply next week to start the world’s first patient trial of the pioneering technology.

Successful pre-clinical experiments in Britain and the US have shown that the technique can detect DNA defects in embryos with great accuracy. The Human Fertilisation and Embryology Authority (HFEA) is expected to clear the research team to start treating patients in the autumn.

The test, developed by Professor Alan Handyside, of the Bridge Clinic in London, promises to help families affected by inherited illnesses, such as cystic fibrosis and spinal muscular atrophy, to have healthy children.

It is capable of identifying any of the 15,000 known genetic disorders, only 2 per cent of which can be picked up by existing embryo screening. It can also identify chromosomal defects that prevent normal development.

The technique, known as karyomapping, will, however, deepen controversy over “designer babies” by widening the range of genetic characteristics for which embryos can be screened. It can identify multiple genetic variations, potentially allowing scientists to test for combinations that together confer higher risks of conditions such as diabetes, heart disease and cancer.

In theory, it could also be used to select an embryo with a particular eye colour, or with genes that affect height, although such applications would not be approved by the HFEA.

Checking for the multiple genes that control most socially desirable traits would also be impossible in practice, because hundreds of embryos would be needed to guarantee the desired profile.

The advance has further contentious implications for privacy and consent, because it could be used to provide parents with a genetic profile for their children, detailing their future susceptibility to disease. The children would have no chance to consent to the collection of such data.

Karyomapping works by tracking how chunks of genetic material are passed from generation to generation, to determine whether or not a mutation has been inherited by a particular IVF embryo.

Unlike existing screening techniques, there is no need to identify the precise mutation affecting a family before testing for it.

Gary Harton, of the Genetics and IVF Institute in Fairfax, Virginia, collected DNA from five embryos that had already been screened for the mutation that causes cystic fibrosis, using existing methods. He then sent the data to Professor Handyside, to retest using karyomapping.

Professor Handyside said: “This is a truly universal test for genetic defects in embryos. If you know there’s a faulty gene, you can map it and work out whether it’s been inherited. You don’t need to know what the mutation is, so you can apply it to anything.”

Mr Harton said: “This is the first time the technique has been tested on actual clinical samples, and it demonstrates that karyomapping can provide highly accurate analysis. It gives us the pre-clinical information we need to move to patient trials.” The trial is likely to involve patients at both the Bridge Centre and the Genetics and IVF Institute, involving 10 to 20 patients. Professor Handyside said that he expected the test to become more widely available within a year.

The test will initially cost between £1,500 and £2,500 — about the same as older methods of embryo screening — but the cost is likely to fall as technology improves. Patients involved in the trial will get free screening, though they will have to fund the cost of their IVF treatment.

Some couples who know they carry a genetic disease have been able to screen their embryos since 1989, using a technique called pre-implantation genetic diagnosis, but its potential has been limited by technical problems.

Geneticists must identify the precise mutation that affects each family before they can test for it, which can take more than a year, and costs several thousand pounds. This still cannot be done for many diseases, particularly rare ones.

The strength of karyomapping is that there is no need to identify precise mutations: scientists need only know where in the genetic code a mutation resides, and can then work out whether or not it has been passed on to an embryo.

DNA samples are first obtained from the parents and a close relative, usually a child who has the disease in question. This can be done using a non-invasive cheek swab.

This information is then compared with DNA from an embryo, obtained by a biopsy in similar fashion to PGD, to map how its chromosomes are built from the genetic material of its four grandparents. The map can determine whether the embryo has inherited chunks of chromosome that contain any faulty gene.

Copyright 2009 Times Newspapers Ltd.