by Dr. Heather Kuruvilla
What if we could actually treat the root cause of conditions like Down’s Syndrome, rather than simply ameliorating symptoms? Although the life expectancy of Down’s Syndrome patients has increased dramatically in the past few decades, and is now approximately 60 years of age, patients continue to experience serious medical conditions such as congenital heart defects, hearing loss, and a susceptibility to Alzheimer’s Disease (National Down Syndrome Society). Since all of these conditions correlate with the presence of an “extra” 21st chromosome, gene dosage is hypothesized be the root cause of these issues. So, can we simply turn that extra chromosome off?
In human females with a normal chromosomal composition, somatic (body) cells contain two X-chromosomes. Normally, in each cell, one X-chromosome is completely silenced. Recently, scientists have discovered how long, non-coding RNAs (lncRNA) interact with proteins to cause inactivation of the entire X-chromosome. It is hoped that understanding this mechanism will eventually lead to better treatments of autosomal trisomies, such as the most common, Down’s Syndrome, as well as trisomy 14 and trisomy 18, which are sometimes viable. According to Genetic Engineering and Biotechnology News:
This information soon may have clinical applications. The Xist lncRNA silences the X chromosome simply because it is located on the X chromosome. However, previous studies have demonstrated that this RNA and its silencing machinery can be used to inactivate other chromosomes, e.g., the third copy of chromosome 21 that is present in individuals with Down’s syndrome.
Click here for more information on this discovery.