Genetic birth defects; mental retardation, health problems, characteristic physical features.

Trisomy 21

Most common type of Down syndrome.  Extra chormosome is present in all cells. Risk factors include:

  • Pregnancy at age 35 and older. The older, the higher the risk
  • Previous pregnancy with Down Syndrome


Some cells have extra chromosome.


The only type of Down syndrome that can be inherited. Risk factors:

  • Family history of Down Syndrome
  • Previous pregnancy/pregnancies with Down Syndrome

Body shape and size

  • Short stature (height)
  • Low muscle tone (hypotonia). Stomach sticks out caused by weak muscles
  • A short, wide neck
  • Short, stocky arms and legs

Face shape and features

  • Slanted eyes.
  • Nasal bridge is the flat area between the nose and eyes.
  • Small ears, or low set
  • Irregularly shaped mouth and tongue
  • Irregular and crooked teeth

Health problems

  • Intellectual disability
  • Heart defects
  • Hypothyroidism, celiac disease, and eye conditions
  • Respiratory infections, constipation, hearing problems, or dental problems.
  • Depression or behavior problems associated with ADHD or autism.


Screening tests include:

  • Combined first trimester screen: 9 to 13 weeks of pregnancy, measures hormones
  • Second trimester triple screen: This blood test measures hormone and protein levels along with estriol, a hormone made by the mother and the unborn baby.
  • Second trimester quad screen. looks at another hormone made by the placenta called inhibin-A.
  • Integrated screening. This includes the combined first trimester screen and the second trimester quad screen

Cell-free DNA (cfDNA) finds small fragments of fetal DNA floating in the mother’s blood and tests them. It can be done after 10 weeks of pregnancy.

Diagnostic Tests

The different diagnostic tests during pregnancy are:

  • Amniocentesis: done between weeks 14 and 18.
  • Chorionic villus sampling: done between 9 and 11 weeks. This test takes a sample from the placenta.
  • Percutaneous umbilical blood sampling (PUBS): at least 18 weeks. This test takes a sample of the baby’s blood from the umbilical cord. It is the most accurate of the three tests.



Although there’s no cure for Down Syndrome, children and adults with this condition may still have productive and content lives. Basic skills may be taught and learned.

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