Down Syndrome

What is Down syndrome?

Down syndrome, also known as trisomy 21, is a condition that occurs when someone is born with an extra copy of chromosome 21. This chromosomal change can result in physical and mental changes. 

Down syndrome is the most common chromosomal disorder, as one in every 700 babies are born with it in the United States. 

What are the symptoms of Down syndrome?

The symptoms of Down syndrome can vary widely between affected individuals. In terms of mental symptoms, those with Down syndrome often speak slowly and have IQs in the lower range. 

Physical symptoms include a short neck, a flattened face, slanted and almond shaped eyes, white spots on the iris, small ears, a tongue that sticks out of the mouth, a single palmar crease, small hands and feet, shorter height, poor muscle tone, loose joints, and small, curved pinky fingers. 

Other conditions may also arise in those with Down syndrome, including hearing loss, obstructive sleep apnea, heart defects, eye diseases, and ear infections. 

What causes Down syndrome?

Down syndrome occurs due to an extra copy of chromosome 21. About 95% of those with Down syndrome see a complete extra copy, while the other five percent may have different mutations with this chromosome. About 3% of affected individuals have an extra copy of this chromosome, but it is attached to another chromosome rather than existing on its own. The remaining 2% have mosaic Down syndrome, meaning that only some of their cells have the extra copy of chromosome 21. 

Medical professionals are unsure as to why this extra chromosome occurs, but they have identified risk factors. If a mother becomes pregnant after age 35, they are at a higher likelihood of having a child with Down syndrome. 

How is Down syndrome diagnosed?

Two forms of tests can be performed before the child is born: screening and diagnostic. The difference is that the former does not definitively tell whether a child has the disorder but is less invasive, whereas the second confirms a diagnosis but poses more risk to the mother and child. 

Screening tests are made up of a combination of blood tests and ultrasounds. Diagnostic tests include chorionic villus sampling (CVS), amniocentesis, and percutaneous umbilical blood sampling (PUBS). 

What are the treatments for Down syndrome?

Speech, occupational, and physical therapy are recommended for those with Down syndrome in order to help them realize their full potential. Special programs are often available for affected individuals as well. 

Where can I find out more about Down syndrome?

• • CDC
  • National Down Syndrome Society
  • Mayo Clinic