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Hot on the heels of a ball-court killer.

Hot on the heels of a ball-court killer

Researchers appear tantalizingly close to identifying the genetic and biochemical basis of Marfan's syndrome, an inherited disorder that leaves one in 10,000 Americans with progressively faulty skeletons, hearts, eyes and lungs. Those inheriting this mysterious syndrome generally grow unusually tall, lanky and long-fingered. Many die before age 40.

The puzzling disorder gained recent attention when it took the lives of Olympic volleyball star Flo Hyman and University of Maryland basketball player Chris Patton. Both died suddenly from exertion-induced bursting of the major blood vessel leading from the heart -- the result of a gradual, hereditary weakening in that vessel's wall. Discovering the gene responsible for Marfan's would help researchers develop prenatal tests for the disorder, and might point the way toward novel therapies, says Reed Pyeritz of the Johns Hopkins University School of Medicine in Baltimore.

Three new studies provide important clues about Marfan's underpinnings.

People with Marfan's syndrome lack sufficient amounts of a widely distributed body protein called fibrillin, according to Pyeritz, David W. Hollister (now at the University of Nebraska Medical Center in Omaha) and their colleagues at Hopkins, who collaborated with researchers at the Shriners Hospital for Crippled Children in Portland, Ore. Without fibrillin, the body's billions of cells cannot surround themselves with microfibrils -- tiny filaments of connective tissue that provide structural support in the spaces between cells. The finding, reported in the July 19 NEW ENGLAND JOURNAL OF MEDICINE, means that in Marfan's, "there's something wrong with the scaffolding, or glue, that holds you together," Pyeritz says.

Physicians have long theorized that Marfan's is a connective-tissue disease. But until now, they weren't sure which of the many connective-tissue components held the defect. In recent years, scientists have ruled out onetime candidates elastin and collagen. Now, with good evidence that the syndrome results from a disabled fibrillin gene, the race is on to pinpoint the location of that gene.

But where to start? With no knowledge of the fibrillin connection, chromosomal cartographers for years have sought the Marfan's gene by tracking the syndrome's inheritance pattern in affected families. Six months ago the search narrowed to two of the 23 chromosome pairs present within human cells. Now, Pyeritz says, Finnish researchers appear to have pegged the gene to chromosome-15. If the finding proves correct, researchers will focus their search for the fibrillin gene on that chromosome.

The unpublished Finnish study involved about 20 patients in three families, but has yet to be repeated in the United States, Pyeritz says. "Obviously, many of us are now scrambling around with our markers for chromosome-15 and looking at our Marfan's families," he says.

Additional unpublished research led by Shriners Hospital geneticist Lynn Y. Sakai has scientists closing in on the killer gene from yet another front. After more than a year of genetic screening tests performed on Marfan's patients' cells, the team has now found and cloned a stretch of DNA that appears to be part of the fibrillin gene. The newfound DNA sequence "spells out" directions that a cell would need to make a fibrillin fragment. But while the researchers have found the sequence in cells, they still don't know which chromosome carries this sequence. If, as scientists hope, the fibrillin gene and Marfan's gene both reside on chromosome-15, researchers may at last confirm that the Marfan's gene is but a mutated form of the fibrillin gene.

Though, the Marfan's gene today remains unmapped, Pyeritz says, "Check back in a couple of weeks."
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Title Annotation:genetic and biochemical research on Marfan's syndrome
Author:Weiss, Rick
Publication:Science News
Date:Aug 4, 1990
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