What is this crazy idea of “turning off” a chromosome and how will it benefit us? Well, in a recent scientific discovery Dr.Jeanne Lawrence and her team found a way to turn off the extra chromosome that causes Down syndrome. This discovery talked about in an article written by Jennifer Wong has opened new perspectives on treating the syndrome. Now now, this is not a cure to Down syndrome, it is way to eliminate the symptoms. Still an astonishing feat! To examine this we must first simply look at what Down syndrome is. Down syndrome is caused by the presence of an extra chromosome- chromosome 21. So we can fully understand chromosome 21 in it’s entirety is here is some more information. People unaffected by this syndrome have 22 chromosomes, however in the case of Down syndrome chromosome 21 gets copied three times instead of the regular two- causing an extra chromosome. This genetic disorder is quite common in our present day. Down syndrome is known for causing intellectual issues, heart problems and early Alzheimer’s disease. To add, this is a great website which explains Down syndrome in further detail.

 

The extra chromosome 21 in down syndrome

The extra chromosome 21 in down syndrome

So what is this ground breaking discovery? Dr.Lawrence, at the University of Massachusetts, tested the idea of “shutting  down” chromosome 21. She and her team had discovered that the gene specifically involved with X-Chromosome  inactivation could be used to “turn off” the extra chromosome. This gene is known as XIST- X-inactive specific transcript. XIST has a non-coding RNA covering. This causes a string of chromosomal changes that mute gene expression. Dr.Lawrence wondered if this gene could be used to shut down chromosome 21. She and her team set up an experiment- to insert the XIST gene into the extra chromosome and see if it causes the inactivation they were hoping for. But doing so is not as simple as it sounds. How do we insert a gene into a chromosome with out fault? The answer to this is an editing enzyme called the zinc finger nuclease- an enzyme that can insert genes into chromosomes while making little to no mistake. To  ensure certainty  the team used doxycycline, a drug that helped to induce an expression from the gene.

After conducting this experiment Dr.Lawrence and her team found that the expression induced by the doxycycline on the XIST gene could effectively inactivate or in other words, turn off, the extra chromosome. This turned it into a Barr body (a condensed X chromosome). The experiment had worked! Dr.Lawrence’s paper on the experiment can be found here. The inactivation of chromosome 21 eliminated the symptoms of Down syndrome. A brilliant discovery sure to pave the way for further exploration of cures to Down syndrome, a syndrome which effects many people in our world today. What do you think of this amazing find and how it will benefit those affected by Down syndrome?

Article Source:

http://www.science20.com/quotsciencequotstruck_bookworm/turning_extra_chromosome_down_syndrome-116789

Picture Credit:

http://commons.wikimedia.org/wiki/File:Boy_with_Down_Syndrome.JPG

 

 

 

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