Gene scans crack medical cases


Researchers prepare reagents for the DNA sequencing of patient samples on Baylor University’s campus in Houston. (The Associated Press)

Published: Wednesday, October 23, 2013 at 2:54 p.m.
Last Modified: Wednesday, October 23, 2013 at 2:54 p.m.

They were mystery diseases that had stumped doctors for years — adults with strange symptoms and children with neurological problems, mental slowness or muscles too weak to let them stand. Now scientists say they were able to crack a quarter of these cases by decoding the patients' genes.

Their study is the first large-scale effort to move gene sequencing out of the lab and into ordinary medical care, and it shows that high hopes for this technology are finally paying off.

"This is a direct benefit of the Human Genome Project," the big effort to decode our DNA, said Dr. Christine M. Eng of Baylor College of Medicine in Houston. "We're now able to directly benefit patients through more accurate diagnosis."

She led the study, which was published recently by the New England Journal of Medicine. It gives results on the first 250 patients referred to Baylor for a newer type of sequencing — just the DNA segments that hold the recipes for all the proteins the body needs. That's only about 1 percent of the whole genome.

Already, three people tested at Baylor were found to have a muscle disorder that can cause respiratory problems and even death. The condition is aggravated by infections and stress, and there are drugs to treat those, Eng said.

In other cases, having a diagnosis helped parents like Lindsey and Brandon Collier decide whether to have more children. The Colliers, who live in Georgetown, Texas, about 30 miles north of Austin, searched for years for an answer to what was plaguing their son, Cannon, now 4.

"He was a pretty floppy baby" with problems eating, Lindsey Collier said. "We weren't getting any answers and they were just all over the map on everything they were testing for."

Genetic counselors said the problem was not likely to occur in other offspring, so the Colliers had a second child. Their 6-week-old daughter, Smith, is fine, and Cannon is being helped now by intensive physical therapy.

In the study of the first 250 patients at Baylor, 62 were found to have gene flaws. In 33 cases, only one faulty copy of a gene was responsible. In 16 other cases, both copies of a gene were bad. Four patients had problems in two different genes. Nine patients had faulty genes on the X chromosome. Since boys have only one copy of that sex chromosome, those disorders mostly affect that gender.

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