The study, published in the Science Translational Medicine journal, offers no direct link to a treatment for humans but scientists are hopeful it may offer a path towards future breakthroughs.

There is no cure for Down syndrome, which is caused by the presence of an additional chromosome and results in intellectual disabilities, distinctive facial features and other health problems.

The team at Johns Hopkins University of Medicine, in Baltimore, used lab mice that were genetically engineered to have extra copies of about half the genes found on human chromosome 21, leading to Down syndrome-like conditions such as smaller brains and difficulty learning to navigate a maze.

On the day the mice were born, scientists injected them with a small molecule known as a sonic hedgehog pathway agonist.