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DNA Chips — herald greater accuracy in genetic screening
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The coming of DNA chips
will make it both relatively simple and very inexpensive to screen people in the community to determine whether they carry certain genetic disorders, the annual conference of Women's Health Australia was told.
Professor Bob Williamson, director of Murdoch Children's Research Institute and professor of medical genetics at the University of Melbourne, said the DNA chip has a very powerful technical range, and once these can be adapted for use in the community, it will become possible to offer testing to all couples.
He said although DNA chip technology is still in the experimental stages, it is being used widely in research and is beginning to be used in diagnosis.
The Murdoch Institute is developing a DNA chip to look at hearing disorders in infants, because many of the genes for deafness have now been identified.
The great advantage of the chip is that it can carry 100,000 sequences on a single chip.
This gives an enormous flexibility for looking at many conditions simultaneously, said Professor Williamson.
The major problem is determining whether people will want this information, he cautioned.
"My personal experience is that most couples want to avoid the birth of seriously handicapped children and will want to make use of this information in most cases by not proceeding with such a pregnancy."
In the case of Down syndrome and other chromosomal abnormalities, the new techniques of early ultrasound scanning and early maternal serum scanning can be put together to give a lower false positive rate and to offer a number of opportunities for women to make choices during pregnancy which increase both the safety and the accuracy of the procedure, he said.
Professor Williamson predicted that over the next 5-10 years we will see further major advances both for single gene disorders, for the impact of genetics and its interaction with environment in complex disorders, and for chromosomal abnormalities.
"The breakthrough which everyone would like to see would be to find a way to get fetal cells from the maternal circulation.
"So far this has been a frustrating and disappointing area."
It is obvious there are a small number of fetal cells there but no one yet has a reliable technique to extract them, he said.
If such as technique were to be developed, healtlhcare professionals would be in a position to offer what most couples want - an accurate and noninvasive diagnostic procedure for major handicap in the fetus during pregnancy.
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