Washington: US researchers may have identified a compound that appears to reverse the learning deficits associated with Down Syndrome in lab mice.

While the use of the compound, a small molecule known as a sonic hedgehog pathway agonist, has not been proven safe for testing on people with Down Syndrome, researchers said Wednesday their experiments hold promise for developing drugs similar to it, reports Xinhua.

Down Syndrome is one of the most common chromosomal abnormalities in children, and a leading cause of intellectual disability.

It occurs when people have three instead of the two usual copies of the chromosome 21.

As a result of this "trisomy", people with Down Syndrome have extra copies of more than 300 genes, leading to intellectual disabilities, distinctive facial features and sometimes heart problems and other health effects.

In their study, the researchers from the Johns Hopkins University and the US National Institute of Health conducted experiments on mice to give them extra copies of about half of the genes found in humans.