Deadly Disorder Linked to Cholesterol Accumulation in Brain

Scientists have discovered that the mutated Huntington's protein interacts with another protein to cause a dramatic accumulation of cholesterol in the brain. Their finding was reported in the December 15, 2006, issue of Human Molecular Genetics.

This protein interaction may help to explain how the deadly Huntington's disease affects the brain. Huntington's disease, also called Huntington's chorea or St. Vitus' dance, is a progressive, degenerative condition that causes nerve cells in the brain to waste away. Symptoms include uncontrolled movements, emotional disturbances, and mental deterioration.

The mutant protein of Huntington's disease attacks the railroad system of brain cells and impairs transport of essential materials required for neurons to function. When this transportation system goes awry in the parts of the brain affected in Huntington's disease, motor skills, cognitive skills, and even speech can be affected. A patient with Huntington's disease cannot move without shaking, and physical control gradually deteriorates, often with accompanying personality changes, depression, and an increased risk of suicide.

The new findings provide the first direct link between Huntington's protein and the protein that controls capture and trafficking inside the cell. The research suggests a possible means by which Huntington's disease functions. Currently, nobody knows how the disease is incurred or spreads, so the new information is critical and provides a clear path for investigators to follow.

"Our discovery that the mutant Huntington's disease protein derails the cholesterol delivery system and causes cholesterol accumulation in neurons provides us with key results and solid clues to the mechanism of this disease,” said Cynthia McMurray, Ph.D., a molecular biologist at the Mayo Clinic (Rochester, MN, USA).

Around 30,000 people in the United States alone have Huntington's disease, while another 150,000 carry the gene and have a 50% risk of passing it on to their children. The disease is easily diagnosed by a blood test, but symptoms usually do not appear until middle age.



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