Down’s Syndrome is a birth defect caused by the presence of a supernumerary chromosome on the 21st pair. Instead of having a total of 46 chromosomes as is habitual, a person with Down’s syndrome has 47.

Normally, men and women have 23 pairs of chromosomes : two X chromosomes for women and an X and Y for men.

The presence of these 3 chromosomes on the 21st has consequences but does not deprive them of skills and abilities.