Trisomy 21: scientists neutralise the extra chromosome

Publié le : 19 July 2013

  In the United States, a team of research scientists led by Jeanne Lawrence at the Massachusetts University School of Medicine, has succeeded in "neutralising the excess chromosome responsible for trisomy 21 in cultured cells". This treatment known as "chromosome therapy", "should […] help to shed light on this disease and even open up new treatment avenues one day". The research studies were published in the Nature journal on 17 July 2013.       

A healthy human being normally has 23 pairs of chromosomes, i.e. 46 chromosomes in total, whereas subjects presenting with trisomy 21 have three 21 chromosomes instead of two. According to Jeanne Lawrence, "It has been impossible to correct a whole chromosome up until now, even in vitro". To make this a reality, "scientists inserted a gene in the extra chromosome and used it to ‘break the circuit’ in some way". The "XIST" gene was used.  This gene "is involved in embryonic development to inactivate one of the two female X chromosomes in mammals". In concrete terms, experience was acquired "using cells harvested from trisomy subjects and reprogrammed to return to a virtually embryonic state […] in order to obtain different types of body tissues". The induced pluripotent stem (iPS) cell technique was used.
The team therefore went on to another stage which involved testing "chromosome therapy" to establish whether it could "correct diseases in mice […] presenting with trisomy 21". According to Jeanne Laurence, the first results should be available "12 months from now ".

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