University of Washington scientists have succeeded in removing the extra copy of chromosome 21 in cell cultures derived from a person with Down's syndrome. In Down syndrome, the body's cells contain three copies of chromosome 21, rather than the usual pair.
A triplicate of any chromosome is a serious genetic abnormality called a trisomy. Trisomies account for almost one-quarter of pregnancy loss from spontaneous miscarriages, according to the research team. Besides Down syndrome (trisomy 21), some other human trisomies are extra Y or X chromosomes, and Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13), both of which have extremely high newborn fatality rates.
In their report appearing in the Nov. 2 edition of Cell Stem Cell, a team led by Dr. Li B. Li of the UW Department of Medicine described how they corrected trisomy 21 in human cell lines they grew in the lab. The senior scientists on the project were gene therapy researchers Dr. David W. Russell, professor of medicine and biochemistry, and Dr. Thalia Papayannopoulou, professor of medicine.
The targeted removal of a human trisomy, they noted, could have both clinical and research applications. In live births, Down syndrome is the most frequent trisomy. The condition has characteristic eye, facial and hand features, and can cause many medical problems, including heart defects, impaired intellect, premature aging and dementia, and certain forms of leukemia, a type of blood cancer.
"We are certainly not proposing that the method we describe would lead to a treatment for Down syndrome," Russell said. "What we are looking at is the possibility that medical scientists could create cell therapies for some of the blood-forming disorders that accompany Down syndrome."
For example, he said, someday Down syndrome leukemia patients might have stem cells derived their own cells, and have the trisomy corrected in these lab-cultured cells. They cou
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University of Washington