BEIJING, July 7 (Xinhuanet) -- U.S. scientists from Stanford University have found mental retardation in people with Down syndrome may be caused by a mutated gene, according to a new study published in the Journal Neuron Wednesday.

    The finding suggests that the mental decline in the people with Down syndrome may get controlled in the future by interfering with the gene expression.

    "If we can decrease the expression of this gene we may be able to provide something more than supportive care to people with Down syndrome," said neurologist Dr. William Mobley of the Stanford University School of Medicine and Lucile Packard Children's Hospital in California.

    Down syndrome is the most frequent genetic cause of mental retardation and affects one out of 800 babies born. It is caused when people have an extra copy of chromosome 21, making three instead of two.

    It causes early learning difficulties, sometimes causes childhood heart disease and leukemia. Most people with Down syndrome develop Alzheimer's disease by the age of 40.

    In the study, the scientists employed genetically engineered mice to find the gene called App - short for amyloid precursor protein.

    Mutations of this gene can cause early-onset Alzheimer's disease in otherwise healthy people.

    The mice carried three copies of App gene just as people with Down syndrome have three copies of chromosome 21. When the App gene in the third copy was deleted, the mice became more normal.

    The study is the first step to find a treatment at a molecular level for Down syndrome.

    Scientists acknowledged more work is needed to examine other genes and find possible ways to reduce the activity of the gene. Enditem

(Agencies)