Down syndrome and Trisomy 21

Down syndrome is a genetic abnormality that occurs when you rise to a chromosome ( chromosome 21 ) in the development of a sperm or an egg cell . When the sperm and the ' oocyte give birth to a zygote , the two gene pools are joined by determining the presence of three copies of chromosome 21 instead of due1 . With each cell division , this extra copy of chromosome 21 is found in every cell . This is the condition which is defined as " Trisomy 21 " . Down syndrome is the most frequent among the identified genetic abnormalities . It can cause developmental delays intellectual and physical.


•    Approssimativamente dal 60 al 70% delle donne effettuano un test prenatale2
•    La maggiorparte dei bambini con sindrome di Down sono nati da donne under  353
•    On average, Down syndrome occurs in one in every 691 children born vivi4
•    There are about 6 million people in the world with Down Syndrome5


  1. "American Pregnancy Association." American Pregnancy Association. American Pregnancy Association, n.d. Web. 12 Oct. 2012.
  2. Frost and Sullivan, Strategic Analysis of the U.S. Prenatal Testing Market, N940-55, 2011 6. "Surprising Facts about Birth in the United States." BabyCenter. BabyCenter, L.L.C., Aug. 2011. Web. 12 Oct. 2012.
  3. California. Department of Public Health. Genetic Disease Screening Program. The California Prenatal Screening Program Provider Handbook. N.p.: n.p., n.d. Web. 12 Oct. 2012.
  4. "Facts About Down Syndrome." National Association for Down Syndrome. National Association for Down Syndrome, n.d. Web. 12 Oct. 2012.
  5. Steenhuysen, Julie. "Down Syndrome May Hold Key to New Alzheimer's Treatments."Reuters. Thomson Reuters, 25 Sept. 2012. Web. 01 Oct. 2012.