CHARGE, which affects 1 in 10,000 babies, is an acronym whose letters stand for some of the more common symptoms of the condition: coloboma of the eye, heart defects, atresia of the choanae, retardation of growth and/or development, genital and/or urinary abnormalities, and ear abnormalities and deafness. Originally, the researchers were examining the tumor-suppressive properties of the protein, called p53, not investigating developmental disorders. But when a mouse model developed a strange set of deficiencies, the researchers followed a trail of clues that led them to link p53 with CHARGE syndrome. "It was a very big surprise and very intriguing," said Jeanine Van Nostrand, Ph.D., lead author of a paper describing the research and a former Stanford graduate student, now at The Salk Institute for Biological Studies. "p53 had never before been shown to have a role in CHARGE." The paper was published online on August 3, 2014 in Nature. The senior author is Laura Attardi, Ph.D., professor of radiation oncology and of genetics. The researchers originally created a mouse model that expressed a mutated form of the protein, known as p53, to investigate the behavior of p53 in suppressing tumors. Mice expressing only the mutated protein survived. But to the team’s surprise, heterozygous mice, or those with one copy of the mutated p53 and one normal copy, developed symptoms of CHARGE and died in utero. p53 is a cellular quality-control regulator. When it spots an ailing cell, it triggers other proteins to kill the cell or arrest its division. In a developing human or mouse, other proteins switch off p53 so it doesn't inadvertently kill important cells. The mutated form of p53 created by the researchers had a disabled off-switch, but it also couldn't communicate with other proteins to spark the cellular death.
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