Madison, Wis. Down syndrome, the most common genetic form of intellectual disability, results from an extra copy of one chromosome. Although people with Down syndrome experience intellectual difficulties and other problems, scientists have had trouble identifying why that extra chromosome causes such widespread effects.
In new research published this week, Anita Bhattacharyya, a neuroscientist at the Waisman Center at the University of Wisconsin-Madison, reports on brain cells that were grown from skin cells of individuals with Down syndrome.
"Even though Down syndrome is very common, it's surprising how little we know about what goes wrong in the brain," says Bhattacharyya. "These new cells provide a way to look at early brain development."
The study began when those skin cells were transformed into induced pluripotent stem cells, which can be grown into any type of specialized cell. Bhattacharyya's lab, working with Su-Chun Zhang and Jason Weick, then grew those stem cells into brain cells that could be studied in the lab.
One significant finding was a reduction in connections among the neurons, Bhattacharyya says. "They communicate less, are quieter. This is new, but it fits with what little we know about the Down syndrome brain." Brain cells communicate through connections called synapses, and the Down neurons had only about 60 percent of the usual number of synapses and synaptic activity. "This is enough to make a difference," says Bhattacharyya. "Even if they recovered these synapses later on, you have missed this critical window of time during early development."
The researchers looked at genes that were affected in the Down syndrome stem cells and neurons, and found that genes on the extra chromosome were increased 150 percent, consistent with the contribution of the extra chromosome.
However, the output of about 1,500 genes elsewhere in the genome was strongly affected. "It's not surprising t
|Contact: Anita Bhattacharyya|
University of Wisconsin-Madison