Gene mutation exacerbates eye defect in inherite...( Bar Harbor Maine While studying mice w...)

Bar Harbor, Maine While studying mice with a mutant gene whose counterpart causes inherited glaucoma in humans, researchers have discovered a second gene mutation that worsens the structural eye defect that causes this type of glaucoma. The newly discovered gene mutation affects production of L-DOPA. The researchers suggest that it might be feasible to prevent glaucoma by administering L-DOPA, which is used in treating Parkinson's disease.

The researchers, led by Jackson Laboratory Staff Scientist Simon W. M. John, a Howard Hughes Medical Institutes investigator, reported their findings in the March 7, 2003, issue of the journal Science. John's colleagues included Richard Libby and Richard Smith of The Jackson Laboratory, and Frank Gonzalez of the National Cancer Institute.

In their studies in mice, the researchers explored how the absence of the gene that encodes the protein Cyp1b1 -- the same defect that occurs in humans with primary congenital glaucoma (PCG) -- affects development of glaucoma. In examining the mice, the scientists found malformations of ocular drainage structures that normally control pressure as the liquid aqueous humor flows out of the eyeball. These eye abnormalities are known as anterior segment dysgenesis.

According to Smith, who has treated patients with PCG, the ability to pinpoint the abnormalities in mice will most likely advance understanding of how the disease develops in humans. "The frustrating thing about attempting to understand human PCG is that there have been very few cases reported in which the patients haven't already had glaucoma for many years and been subjected to surgery and multiple medications," said Smith. "So, by the time we can examine the human tissue, the anatomic defect is very difficult to determine."

According to John, these anatomic abnormalities are an underlying cause of the severe glaucoma that affects people with PCG. Although the disorder is relatively uncommon -- occurring
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Contact: Joyce Peterson
joyce@jax.org
207-288-6058
Jackson Laboratory
7-Mar-2003

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