Recent breakthroughs may lead to pharmacological treatments for the chromosomal disorde
People born with Down syndrome have always been considered to be incurably developmentally delayed—until now. In the past few years a number of laboratories have uncovered critical drug targets within disabled chemical pathways in the brain that might be restored with medication. At least two clinical trials are currently studying the effects of such treatments on people with Down syndrome. Now geneticist Roger Reeves of Johns Hopkins University may have stumbled on another drug target—this one with the potential to correct the learning and memory deficits so central to the condition.
Down syndrome occurs in about one in 1,000 births annually worldwide. It arises from an extra copy of chromosome 21 and the overexpression of each of the 300 to 500 genes the chromosome carries. “If you go back even as recently as 2004, researchers didn't have much of a clue about the mechanisms involved in this developmental disability,” says Michael Harpold, chief scientific officer with the Down Syndrome Research and Treatment Foundation. But all that has changed. “In the past six or seven years there have been several breakthroughs—and ‘breakthroughs’ is not by any means too big a word—in understanding the neurochemistry in Down syndrome,” Reeves says.
This improved knowledge base has led to a series of discoveries with therapeutic promise, including the latest by Reeves. He and his team were attempting to restore the size of the cerebellum in mice engineered to show the hallmarks of Down syndrome. The cerebellum lies at the base of the brain and controls motor functions, motor learning and balance. In people with Down syndrome and in the Down mouse model the cerebellum is about 40 percent smaller than normal. By restoring its size, Reeves hoped to gain a clearer picture of the developmental processes that lead to anomalies in a brain with Down syndrome.
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