Gene test "improves embryo checks"

It will soon be possible to test embryos for the mutations which can cause cystic fibrosis much more quickly using gene chips, researchers have revealed.

Currently, doctors have to test for one at a time, and couples can have to wait up to two months for results.

Researchers from Australia's Monash University used chips which contain thousands of strands of synthetic DNA. Any faulty genes in embryo cells will then show up against the test.

The findings were presented at the European fertility conference in Berlin.

Wait

Cystic fibrosis is a fatal disease in which thick mucous clogs the lungs and pancreas, trapping bacteria and harming digestion.

One in 25 people in the UK are carriers of the faulty CF gene.

The most common mutation is one which leads the body's cells to make abnormal versions of a protein called deltaF508, although there are several other mutations which can cause the condition.

Currently, doctors have to carry out separate tests for each mutation, and couples have to wait at least six weeks for the results.

The researchers found the gene chip, or microarray can be used successfully to detect the deltaF508 mutation with 100% accuracy.

They add that the analysis could be carried out on embryos during preimplantation genetic diagnosis so that only healthy embryos would be transferred to the woman.

PGD is usually carried out on one cell when embryos are around three days old, or contain around eight cells.

The gene chip test would have to be carried out when embryos are five to six days old, and contain around 100 cells.

However, the researchers say tests have shown this is accurate, and does not damage the embryos.

'Excellent advance'

Ms Chelsea Salvado, of the Institute of Reproduction and Development at Monash who worked on the study, said there was no limit to the number of mutations which could be screened for.

"As long as you know the DNA sequence of the mutation, you can screen for whatever you like."

She said the technology could be used to screen for a whole range of faulty genes, including the BRCA1 gene linked to breast cancer.

"Microarray technology will lead to semi-automated genetic testing for both PGD and prenatal diagnosis, providing a rapid diagnosis, thus reducing the stress of couples waiting for a result.

"The introduction of microarray technology could lead to PGD being offered for all genetic diseases in the future."

A spokeswoman for the Cystic Fibrosis Trust told BBC News Online: "This would be an excellent advance.

"Clearly it would be an advance in the speed and accuracy of early diagnosis."

Source: BBC News