Often misdiagnosed as cerebral palsy, A-T usually strikes children before age 2 and confines them to a wheelchair by age 10. Many lose their ability to speak and die in childhood. One in three children also develop lymphoma or leukemia. Adults who carry the mutated A-T gene (ATM), including up to 15 percent of breast-cancer patients, are eight times more likely to develop cancer than the general population.
Dr. Richard Gatti, professor of pathology and laboratory medicine, and Chih-Hung Lai, Ph.D., a postdoctoral researcher at the David Geffen School of Medicine at UCLA, created a new strategy for tricking the ATM gene into overlooking certain types of mutations called premature termination codons (PTCs).
"PTCs are like irregular stop signs located in the middle of the block," explained Gatti. "They stop traffic before it reaches the intersection. We made these stop signs invisible, so traffic continues until it sees the proper stop sign at the end of the corner."
In normal cells, termination codons alert the cell's protein-reading machinery that a protein has reached full length and completed copying. In the mutated genes of A-T patients, PTCs halt the copying of proteins too early, resulting in shortened and unstable ATM proteins.
"Unstable proteins create abnormal cells that can't function properly, producing all of the neurological and immune problems that afflict A-T patients," said Lai, the study's first author.
Lai and Gatti noted that A-T patients whose cells contain no ATM protein suffer
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Contact: Elaine Schmidt
elaines@support.ucla.edu
310-794-2272
University of California - Los Angeles
18-Oct-2004