Down syndrome occurs when a individual is born with an extra chromosome 21, giving them 47 chromosomes instead of the normal 46. It has been universally thought that the disease is caused by the presence of excess levels of proteins associated with the extra chromsome. However recent studies have shown confounding evidence to this notion, and that the disease may be caused by the underproduction of certain proteins, not an overproduction.
According to an article published in ScienceDaily.com, Terry Elton at Ohio State University has shown that individuals with Down syndrome lack a protein found in the brain that "could contribute to the cognitive impairment and congenital heart defects that characterize the syndrome." Upon further research, Elton and his colleagues found that 5 microRNAs sit chromosome 21, and that each of them are over expressed in the the brains, hearts, and tissues of Down syndrome patients. According to Elton, one of these microRNAs is directly associated with cardiovascular disease- microRNA-155. Another key finding is that the overabundance of these 5 microRNAs causes a decreased level of a transcription factor- meCP2- in the brain. As it turns out, this transcription factor has a significant role in the regulation of genes that are known to be associated with neural development. Down syndrome most commonly results in impaired cognitive abilities and congenital heart defects, suggesting a strong link between the elevated presence of these microRNA's with deficient levels of proteins.
According to the Center for Disease Control and Prevention, an estimated 13 out of every 10,000 babies born in the United States each year have down syndrome. There is no treatment available for patients with Down syndrome. This new approach offers several new avenues for which therapeutic treatment may be achieved for individuals with Down syndrome.
Posted by Alexander Norregaard (8)