How Is Trisomy 21 Confirmed? Prenatal and Postnatal Testing Explained

Learn how trisomy 21 (Down syndrome) is confirmed through prenatal tests like amniocentesis and CVS, and postnatal karyotype analysis.

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Trisomy 21 can be confirmed through prenatal tests such as the amniocentesis or chorionic villus sampling (CVS), which analyze fetal chromosomes. Postnatally, a karyotype test on the baby's blood cells will show an extra chromosome 21, confirming the diagnosis.

FAQs & Answers

  1. What is trisomy 21? Trisomy 21, also known as Down syndrome, is a genetic disorder caused by an extra copy of chromosome 21.
  2. How does amniocentesis confirm trisomy 21? Amniocentesis collects amniotic fluid to analyze fetal chromosomes, allowing detection of an extra chromosome 21.
  3. When is chorionic villus sampling (CVS) performed? CVS is a prenatal test performed earlier in pregnancy to obtain placental tissue for chromosome analysis, which can confirm trisomy 21.
  4. Can trisomy 21 be confirmed after birth? Yes, a karyotype test on a baby’s blood cells after birth can confirm the presence of an extra chromosome 21.

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