A novel study involving fruit flies and mice has allowed biologists to identify two critical genes responsible for congenital heart defects in individuals with Down syndrome, a major cause of infant mortality and death in people born with this genetic disorder. In a paper published on November 3, 2011 in the open-access journal PLoS Genetics, researchers from the University of California (UC)-San Diego, the Sanford-Burnham Medical Research Institute in La Jolla, California, and the University of Utah report the identification of two genes that, when produced at elevated levels, work together to disrupt cardiac development and function. Down syndrome, the most common genetic cause of cognitive impairment, is a disorder that occurs in one in 700 births when individuals have three, instead of the usual two, copies of human chromosome 21. “Chromosome 21 is the shortest human chromosome and intensive genetic mapping studies in people with Down syndrome have identified a small region of this chromosome that plays a critical role in causing congenital heart defects,” said Dr. Ethan Bier, a biology professor at UC-San Diego and one of the principal authors of the study. “This Down syndrome region for congenital heart disease, called the ‘DS-CHD critical region,’ contains several genes that are active in the heart which our collaborator, Julie Korenberg, had suspected of interacting with each other to disrupt cardiac development or function when present in three copies. But exactly which of these half dozen or so genes are the culprits? Identifying the genes within the DS-CHD critical region contributing to congenital heart defects is challenging to address using traditional mammalian experimental models, such as mice,” added Dr.
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