Worldwide, Down syndrome occurs in about one in 1,000 births annually.

People born with it are almost always developmentally delayed, some severely. Many also suffer from a suite of health problems that include congenital heart disease, leukemia, thyroid disorders and mental illness.

Since the completion of the mapping of the human genome in 2003, it has been understood that Down Syndrome arises from an extra copy of chromosome 21 and an overexpression of each of the 300 to 500 genes the chromosome carries.

Very recently, there has been a breakthrough in understanding the neurochemistry in Down syndrome, leading to a promising series of discoveries with mice.

Geneticist Roger Reeves of Johns Hopkins University, in attempting to restore the size of the cerebellum in mice engineered to show the hallmarks of Down syndrome, injected newborn Down mice with a chemical that stimulates an important neurodevelopmental pathway that, among other things, orchestrates cerebellum growth. “We were not in fact surprised that we fixed the cerebellum. That was our working hypothesis,” Reeves says. But he had not anticipated that three months after treatment, mice with a restored cerebellum would be able to learn their way around a water maze—a function of learning and memory thought to be controlled by another part of the brain, the hippocampus. The researchers do not yet know whether they inadvertently repaired the hippocampus or whether the cerebellum might be responsible for more learning and memory functions than previously realized.

Though other investigational treatments for Down syndrome target the hippocampus, none has yet targeted this particular chemical pathway. Of the future for Down people, Reeves says, “The possibility of actually giving [them] the ability to improve learning and memory significantly—that’s something I never thought I’d see in my entire career. “And it’s now happening. The game has changed.” K

Source of some of the information contained in this article is “Scientific American Magazine.”