Down syndrome is a genetic disorder caused when abnormal cell division results in extra genetic material from chromosome 21. scientists do not know why some babies wind up with the extra chromosome. This genetic disorder, which varies in severity, causes lifelong intellectual disability and developmental delays, and in some people it causes health problems. chromosomes are large structures found in cells that house thousands of genes. People without genetic abnormalities have 23 pairs of chromosomes, and each pair is given a number between 1 and 23.
Causes : Down syndrome results when abnormal cell division involving chromosome 21 occurs. Human cells normally contain 23 pairs of chromosomes. One chromosome in each pair comes from your father, the other from your mother. These cell division abnormalities result in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of Down syndrome. Any one of three genetic variations can cause Down syndrome. Trisomy 21, Mosaic Down syndrome, Translocation Down syndrome. Research : The gene, called XIST, plays a role in turning off one of the two X chromosomes in female mammals, and the UMMS researchers found that it was effective at repressing the genes across the extra chromosome in their laboratory stem cells.