Now twenty-three, Scott (at left with sister, Carly) was diagnosed with fragile X syndrome–the most frequently inherited cause of mental impairment–when he was nine. His parents sought help in understanding why their middle child was hyperactive, made strange noises, and had difficulty communicating.

“We really noticed the delayed speech by age four. Scott was in speech therapy, but his progress was minimal. His pediatrician wasn’t very helpful, he just kept saying Einstein didn’t talk until he was five,” says Scott’s mother, Gail Heyman, now the director of the Fragile X Association of Georgia. “We didn’t get the answers we were seeking until Scott was diagnosed through genetic testing.”

For more than a decade, the Heymans have worked with Professor of Human Genetics Stephanie Sherman and other researchers at Emory, helping them to understand fragile X, which causes developmental delays as well as problems with learning, motor skills, and memory. Emory’s fragile X program is one of the oldest and most respected in the world.

Fragile X is caused by a mutation in a single gene, as are cystic fibrosis, sickle cell anemia, and hemophilia.

“Everyone has about five to ten mutations among the thousands of genes they carry,” says Sherman. “Sometimes they cause problems, or sometimes they are masked by the presence of other genes.”

In the late 1980s, Sherman noticed that fragile X syndrome did not get passed on to offspring with the same probability as most genetic disorders–a phenomenon that became known as the “Sherman paradox.”

In 1991, Department of Human Genetics Chair Stephen Warren (at right with Stephanie Sherman) discovered the gene, FMR1, that causes fragile X syndrome, and was among the first to develop genetic tests to diagnose the disease. He also found that most affected patients share a common genetic mutation called “triplet repeats,” which helped to explain the Sherman paradox. Warren recently created a new mouse model of fragile X syndrome and is currently testing a variety of drugs on the genetically altered mice.

About 4 to 5 percent of the population carry the gene for fragile X, and about one in four thousand boys and one in eight thousand girls have the syndrome. If one parent is a carrier, a child has a chance of inheriting fragile X.

Most people with fragile X syndrome will live a normal life span, and their prognosis depends on the severity of the disability. Scott’s sister, Carly, has written a book, My eXtra Special Brother, about her family’s experiences.

Warren is confident that with continued research, there soon will be a therapeutic treatment for fragile X. “Our involvement with families like the Heymans,” he says, “make it a very personal quest for us.”–M.J.L.