Down syndrome is a condition caused by a chromosomal alteration, which causes delays in mental and physical development. What characterizes it is the presence of an extra chromosome in the cell nucleus too, specifically in the couple 21. The anomaly in question is known as trisomy 21 and in 98% of cases it is the result of factors still unclear, not attributable to ' inheritance.

There are three types of trisomy 21. In 95% of cases are referred to trisomy 21 full free, so all the body's cells have the anomaly. In 2% of cases occur in the free trisomy mosaicism, so there are both cells with the anomaly that normal cells. In 3% of cases we talk instead of trisomy 21 by translocation, for which the genetic material in most comes from other chromosomes. In the latter case, one of the parents may be a carrier of the translocation, and then the condition would be hereditary.

The causes of the chromosomal abnormality are still unclear. There are several theories about, that lead back trisomy 21 to chemicals and infections. None of these, however, was still confirmed. We know that 9% of conceptions has a trisomy, constant percentage in different populations, and that does not seem to have changed over time. Nevertheless, only 0.6% of children born with a chromosomal abnormality; in other cases, you experience a miscarriage. This suggests that the anomaly is a phenomenon linked to the way the man you play, which is not affected by changing environmental conditions.

You can use special prenatal diagnostic methods to detect the presence of trisomy in the embryo. In recent years it is spreading a non-invasive technique, which starts from a drop of the mother's blood. He is replacing the much more invasive amniocentesis, at least as regards the early stages of screening.

Children with Down syndrome suffer from some mental retardation and development, of varying severity. Speaking immediately with an appropriate rehabilitation, it is possible to recover part of the linguistic functions, motor and neuropsychological. As a result, children can become self down adults and well integrated into the social fabric