A genetic condition that affects about 38,000 people in Italy
Down Syndrome is a particular genetic condition that involves the presence of an extra chromosome in the nucleus of the cells of the people who are affected. Instead of 46 chromosomes, there will be 47 chromosomes in the cells. Specifically, chromosome n.21 is replicated 3 times, in fact Down Syndrome is also known as Trisomy 21. Despite the genetic connotation, in 98% of cases, Down Syndrome is not hereditary.
Among the main consequences and symptoms, this genetic alteration leads to a delay in cognitive, motor and physical development in the Down child. There are also specific physical characteristics of this syndrome such as the particular shape of the eyes, flat and broad face, small toes, excessive distance between the big toe and the second toe, a single fold in the palm of the hands, protruding tongue cause of small oral cavity.
But what can be the causes of Down Syndrome? In reality there are no known causes recognized as such by scientific research. The various hypotheses of external causes (exposure to chemical agents and radiations for example), or internal (endocrine or maternal metabolic alterations) have not been confirmed by research. It is believed, in fact, that the onset of these chromosome anomalies is mostly accidental, a phenomenon linked to human reproduction.
However, the incidence of Trisomy 21 is around 0.6% of those born. Currently in Italy one child out of 1200 is born with Down Syndrome and it is estimated that there are about 38 thousand people suffering from this genetic anomaly. Furthermore, 61% are over 25 and their life expectancy is now 62 years.
Although the causes are unknown, numerous population surveys have shown that the probability that a Down child is born increases with the increasing age of conception of the mother. Furthermore, another risk factor is that of having had a previous child with the syndrome.
Down syndrome can also be diagnosed before birth. Between the sixteenth and the eighteenth week of gestation with amniocentesis (taking a small amount of amniotic fluid with a syringe) or between the twelfth and thirteenth week with the least common, villocentesis (taking the cells from which the placenta will develop) . Usually these tests are recommended for women at risk, ie over 35 years. Among these is the Tri-Test, a predictive test that is done on blood, but is not very reliable.