A cure for Down syndrome in one dose of medicine?

By Casey Frye, CCNN Writer

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Newborn mice with Down syndrome were cured with a single dose of medicine!

Inside every one of our cells, we have what are known as genes, which essentially determine everything that has to do with a person and the way they look. They’re responsible for determining characteristics like eye color, height, hair type, and even gender! Genes are coiled up tight into structures called chromosomes. Normally there are 46 chromosomes inside every one of our cells, however, individuals with Down syndrome have an extra chromosome.

People affected with Down syndrome usually have distinct facial features like flatter faces and slanted eyes. They also tend to have smaller brains, particularly in a structure known as the cerebellum, which is important for controlling movement. If they are treated early for Down syndrome as babies and toddlers, they can go on to lead healthy adult lives. Now, thanks to researchers from Johns Hopkins University and the National Institutes of Health, the disorder can possibly be treated in as little as one dose of medicine!

The researchers say the medicine contains a molecule called SAG, which stimulates the Sonic Hedgehog brain pathway. If the name reminds you of the blue Sega video game character, that’s because it’s exactly where researchers borrowed it from. Although the name is playful, the pathway is very important for brain development! When Johns Hopkins University scientists genetically engineered baby mice to have Down syndrome, and then injected them with medicine, the rodents grew up to have normal-sized brains that functioned just fine.

“Most people with Down syndrome have a cerebellum that’s about 60 percent of the normal size,” says Dr. Roger Reeves, a professor at the Johns Hopkins University School of Medicine. “We treated the Down syndrome-like mice with a compound we thought might normalize the cerebellum’s growth, and it worked beautifully. What we didn’t expect were the effects on learning and memory, which are generally controlled by the hippocampus, not the cerebellum.”

Hooray for the mice! Now, how soon will it be until this medicine is used to treat humans with the disorder? Don’t hold your breath just yet. According to researchers, the Sonic Hedgehog pathway is very sensitive, and using medicine to alter it can have unintended consequences. They need to conduct more studies in order to call it safe for humans to use.

“Down syndrome is very complex, and nobody thinks there’s going to be a silver bullet that normalizes cognition,” said Reeves. “Multiple approaches will be needed.”

Featured image courtesy of Andreas-Photography on Flickr. Image of mouse courtesy of Rama on Wikimedia.