Down’s syndrome, or trisomy 21, is a chromosomal condition that arises from a third, extra, 21st chromosome in a persons genetic code. The 2st chromosome is one of the few small enough that a fetus can survive with a third, but Down’s syndrome causes severe impairment of cognitive ability, motor skills, and physical development. It occurs in one in approximately 800 births and is associated with older mothers.
Using mice, scientists have reproduced the type of neuron damage found in Down’s syndrome patients in an effort to determine the exact mechanism by which it occurs. They found that overgrowth of dendrites, the structures in the brain that connect neurons, inhibits the development of connections between synapses. In other words, the structures get too tangled up for the neurons to form or communicate properly. This is due to overexpression of a particular protein controlled by a gene on chromosome 21 called DYRK1A.
Down’s syndrome can be detected pre-natally. With this research, doctors may one day be able to treat the condition in newborns, reducing the excessive activity of the protein and preventing the associated entanglement. That means these children may not exhibit the learning disabilities common with the condition.