Identical Twins, One with Down Syndrome

      Down syndrome is a genetic disorder which is thought to be caused by the presence of an entire or part of an extra chromosome, or chromosome 21. Down syndrome is usually associated with physical growth delays, characteristic facial features and moderate intellectual disability. The average IQ of an adult with Down syndrome is around 50, which would be around the same as an 8 to 9 year old child. Down syndrome can actually be detected before birth using prenatal screening and other diagnostic tests.
       I found a very interesting article that talks about a case of identical twins born and only one of them had Down syndrome. This is very interesting because it contradicts prior beliefs in this area. The experiment conducted allowed a group of geneticists from Europe to find out how chromosomes dictate the behavior of cells inside the body. Their findings showed that when the gene expression is altered, by the addition of the extra chromosome, it is altered in consistent patterns in every chromosome, and not just with the extra chromosome. Having this opportunity to study such a strange event actually allowed us to understand more about a genetic disorder that effects so many people.