A newly identified compound could preempt and reverse learning disabilities in children born with Down syndrome. In mouse models, a single dose was shown to boost significantly the subjects’ cognitive function, allowing them to perform as well as other mice in behavioral tests. The researchers claim that the findings represent an important step towards more effective treatment methods, as well as a better understanding of the condition’s genetic profile.
According to Johns Hopkins University professor and lead investigator Roger Reeves, the findings build on previous inquiry into the condition’s chromosomal idiosyncrasies. A signature property of a genome affected with Down syndrome is its chromosome 21 “trisomy” – that is, the presence of three copies of chromosome 21 rather than two. Most of the physiognomic and cognitive divergences associated with Down syndrome appear to originate in the 300 genes that the extra chromosome contains.
We’ve been working for some time to characterize the basis for how people with trisomy 21 diverge in development from people without trisomy 21,” Reeves told FoxNews.com. “One of the early things we see is that people with Down syndrome have very small cerebellums, which does a lot more things than we used to think it did.”
The cerebellum, meaning “little brain,” is involved in a wide variety of complex functions, such as balance, coordination, motor skills, and cognitive functions. Impairment in this area leads to an overall reduction in learning capacity and complex thought.
The new compound, known as a sonic hedgehog pathway agonist, counteracts this particular genetic divergence by stimulating cerebellum development. This allows the cerebellum to achieve its normal growth rate. In mouse models, this was shown to have significant bearing on the cognitive deficiencies associated with the condition.
“From that one injection, we were able to normalize the growth of the cerebellum, and they continued to have a structurally normal cerebellum when they grew up,” Reeves explained.
Carol Boys, chief executive of the Down Syndrome Association, told The Daily Mail that the results are of great interest to the Down syndrome community, but stressed that the new compound should not be considered a “cure.” In addition, the compound has yet to be approved for human use.
“As Professor Reeves explains, this is not going to translate into clinical applications for people currently living with the condition but is another step along the path of understanding the complexity of an extra chromosome 21 in every single cell,” she told reporters.
That said, the researchers are confident that the compound will provide new, valuable insight into the condition, and eventually allow scientists to limit cognitive symptoms.
Reeves told reporters, “We’re on the verge of a revolution for expanding the potential of people born with trisomy 21.” Source: I. Das, J.-M. Park, J. H. Shin, S. K. Jeon, H. Lorenzi, D. J. Linden, P. F. Worley, R. H. Reeves, Hedgehog Agonist Therapy Corrects Structural and Cognitive Deficits in a Down Syndrome Mouse Model. Sci. Transl. Med. 5, 201ra120 (2013).