The first evidence that the underlying genetic defect responsible for trisomy 21, also known as Down syndrome, can be suppressed in laboratory cultures of patient-derived stem cells was presented today (October 22) at the opening of the American Society of Human Genetics (ASHG) 2013 annual meeting in Boston, running through October. The ASHG annual meeting is the world's largest gathering of human genetics professionals and a forum for renowned experts in the field.People with Down syndrome are born with an extra chromosome 21, which results in a variety of physical and cognitive ill effects. In laboratory cultures of cells from patients with Down syndrome, an advanced genome editing tool was successfully used to silence the genes on the extra chromosome, thereby neutralizing it, said Jeanne Lawrence, Ph.D., Professor of Cell & Developmental Biology at the University Massachusetts Medical School, Worcester, Massachusetts. Dr. Lawrence and her team compared trisomic stem cells derived from patients with Down syndrome, in which the extra chromosome 21 was silenced, to identical cells from patients that were untreated. The researchers identified defects in the proliferation, or rapid growth, of the untreated cells and the differentiation, or specialization, of untreated nervous system cells. These defects were reversed in trisomic stem cells in which the extra chromosome 21 was muted. “Silencing of trisomy 21 by manipulation of a single gene in living cells in laboratory cells surmounts the first major obstacle to development of potential ‘chromosome therapy,’” said Dr. Lawrence, whose presentation today provided an update to the results that she and her colleagues reported earlier this year in the journal Nature (Jiang et al. 2013). In her ASHG presentation, Dr.
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