Researchers Track an Odd Genetic Disorder
ROBERT SIEGEL, host:
The fruit flies that hover around your fruit bowl may be a nuisance, but geneticists have long viewed them as a resource. Now researchers have shown that a gene first identified in fruit flies is responsible for a devastating disorder in humans. People who inherit two mutated copies of the gene have severe problems seeing, hearing and thinking. As NPR's Joe Palca reports, the new research is an example of how seemingly esoteric work in flies can have relevance to human disease.
JOE PALCA reporting:
For a decade or more Harvard Medical School neurologist Elizabeth Engle has been on the lookout for people with unusual eye movements. She's interested in those people because unusual eye movements can reveal subtle problems with brain development.
Ms. ELIZABETH ENGLE (Neurologist, Harvard Medical School): One of my American collaborators, who's working in Saudi Arabia, Mack Bosley(ph), e-mailed me one day about a year and a half ago and said, `Elizabeth, I've just come across a new syndrome.'
PALCA: Patients with the syndrome Mack Bosley described had peculiar eye movements, but that was just the start.
Ms. ENGLE: The individuals have abnormal horizontal eye movements, and they're born with severe deafness. We also discovered over time that they have abnormalities in their internal carotid arteries. And two of the nine individuals we initially studied had autism.
PALCA: Engle got DNA samples from the Saudi Arabian patients as well as samples from patients in Turkey with a similar problem and started looking for a mutated gene that might be causing the problems. Before the Human Genome Project, it would have taken months or even years, not to mention a lot of luck, to find the right gene. It took Engle and her colleagues 10 days. It's a gene called HOXA1. As they were preparing to publish their finding, Engle recalled a paper she'd read some years earlier. It described eight Navajo and two Apache Indian children with similar problems. University of Arizona scientists wrote that paper.
Ms. ENGLE: So we asked the University of Arizona faculty if we might collaborate with them to study these individuals, and they, too, had a mutation in this gene.
PALCA: So here were three clusters of a strange syndrome, one in the United States, one in Saudi Arabia and one in Turkey, all apparently caused by the HOXA1 gene. The paper describing Engle's research is published in the online edition of the journal Nature Genetics.
HOXA1 is one of a family of genes that play a critical role as an animal begins to develop body parts. HOXA1 is particularly important for normal brain development. Max Tischfield is a graduate student in Engle's lab.
Mr. MAX TISCHFIELD (Graduate Student, Harvard Medical School): Up until this study, we've never really been able to determine what would happen if you had a complete loss of function of a HOX gene.
PALCA: Much of what scientists know about HOX genes comes from work initially done in fruit flies. These genes are responsible for making sure a fly is put together properly, so that wings attach where they're supposed to, for example. Richard Cripps studies fruit fly development at the University of New Mexico. He says it's satisfying to see scientists working on human diseases getting interested in HOX genes.
Mr. RICHARD CRIPPS (University of New Mexico): Those of us who work on flies or mice of fish or frogs, I think this is one of the really big vindications of why we do what we do and why we study what some might think is sort of an esoteric system. And I think that we wouldn't know all that we do know about these genes if it wasn't for sort of the basic research in the model systems.
PALCA: Of course, knowing the gene involved in a disease is not the same as finding the cure for a disease. But as any geneticist will tell you, it's a start. Joe Palca, NPR News, Washington.
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