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DNA biochip for genetic screening

by Medindia Content Team on  December 22, 2001 at 10:30 AM Research News   - G J E 4
DNA biochip for genetic screening
A scientist from the University of Houston has developed a chemical process for building a device that could help doctors predict a patient's response to drugs or screen patients for thousands of genetic mutations and diseases, all with one simple lab test.
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The DNA chip is similar to a computer chip but imbedded with DNA molecules instead of electronic circuitry. It is designed to probe a bilogical sample for genetic information that indicates whether the person has a genetic predisposition for certain diseases or conditions.

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"We have put thousands of strands of DNA onto a chip that can screen for the genes linked to breast cancer, cystic fibrosis or prostate cancer, for example," says Xiaolian Gao, a professor of biochemistry at the University of Houston. "This highly parallel technology allows us to do thousands or tens of thousands of experiments all at once."

She says the quality, suitability and cost of biochip products need to be significantly improved before most researchers or doctors can afford to use them. "The advantage to our biochip is that we bring to the field a flexible, high quality and more cost efficient technology for DNA chips," she says. "Our novel platform technology will allow scientists to make custom-designed biochips containing not only DNA, but other types of molecules, such as RNA, peptides or libraries of organic molecules. Other prevalent technologies do not have the same potential and capabilities as ours."

Gao and her team plan to make the biochips available for fields such as genomics, proteomics, chemical genetics and other new areas. Gao presented information about the versatility of the UH biochip technology at the International Business Communication's Annual Biochip Technologies Conference, Chips to Hits', in San Diego. The process Gao, Zhou and Gulari developed to make the DNA chip involves the use of thousands of micromirrors to project tiny light patterns-less than the diameter of a human hair - onto each postage stamp-sized DNA chip.

Each micromirror can be individually manipulated to reflect light onto an exact location on the DNA chip.Controlled by a computer, the light hits the chip at different spots, where it triggers a chemical reaction. Individual DNA strands are then built up on these locations one by one in a gris-like pattern, and the computer keeps track of information such as where each DNA strand is on the chip.

The strands of DNA affixed on the surface of Gao's chip act as probes, each strand corresponding to a specific gene or a DNA sequence where a complementary strand in biological samples will bind. The DNA contained in a blood or a tissue sample can be placed on the chip, and the person's DNA would then match up with the appropriate probe, like two pieces of Velcro attaching to each other. A detection device indicates which probes found their mark. "If we put specific probes on the chip, we can tell if a person has or doesn't have these genetic codes present, and we can screen for thousands or tens of thousands of genes at once," Gao says.

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