Wednesday, March 24, 2010

A New Theory on Down Syndrome

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, 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)


  1. A lot of research is needed around this area. I think some people are at higher risk for having babies with down syndrome versus others. I know there are some people who go for genetic counseling before having children. Since at least scientists can identify the individuals at higher risk, I wonder if they can come up with something for prevention.

    Posted by Anna Moreno.

  2. When you say there is no treatment available now and that this new approach offers several new avenues for which therapeutic treatment may be achieved for individuals with down syndrome, are you saying that although there is no treatment now there could be treatment in the future because of this new approach? If so, I am curious at why there can't be treatment if Down Syndrome is caused by overproduction of protein but can possible be treated when there is an underproduction of protein.

    Posted by Kayla Perry

  3. I don't know that some families are genetically dispositioned to have a child with down syndrome. This condition occurs when there is a nondisjunction in either the mother or father's 21st chromosome resulting in this trisomic condition. They have found that risk is drastically increased when the mother is over 40 years old. Also it seems like scientists were correct when they said that the problem is overproduction due to the third copy of chromosome 21. The overly produced microRNA's mentioned decrease the levels of other transcription factors in the I feel like the problem is still overproduction of those microRNAs and if we could prevent and increase in them other proteins would be normally produced. It seems to me that treating downs syndrome is an extremely complicated thing as we don't currently have techniques to delete a chromosome present in every cell of the affected individual. However maybe drugs can be produced to help lower the levels of these microRNAs or to help increase the production or activity of the meCP2 transcription factor

  4. It is interesting how scientists assumed for a long time that because an extra chromosome is present in affected individuals, there must be more proteins being synthesized. This study shows that there is actually a decrease in protein expression in affected individuals because miroRNAs inhibit protein formation. I think the most promising aspect of this study is how the low-level proteins in affected mice were increased due to the injection of a microRNA silencer. This, in my opinion, could lead to a cure. Whether this research leads to a cure or not, I think this article demonstrates how important it is for the scientific community to assume nothing and constantly search for new answers.

    Posted by Matt Grazewski

  5. This is vert interesting, it seems that at times scientists can be correct on the location of a particular syndrome's origination point, and yet still be off when it comes to whether it is over production, or whether it under production. I do not like the talk about genetic testing to find out if your child should is afflicted. I feel we are to quick as a culture to test everything. Just becuase a baby has down syndrome does not mean the child is any less valuable.