DNA Testing for Down Syndrome: Non-invasive Testing  

Most of the time, Down syndrome isn’t inherited. It’s caused by an error in cell division during the development of the egg, sperm or embryo. This results in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of Down syndrome. Three genetic variations can cause Down syndrome:

• Trisomy 21. About 95 percent of the time, Down syndrome is caused by trisomy 21. Three copies of chromosome 21 (instead of two) are present in all cells.
• Translocation Down syndrome. Down syndrome can also occur when part of chromosome 21 becomes attached onto another chromosome at conception.
• Mosaic Down syndrome. In this rare (and milder form) of Down syndrome children have an extra copy of chromosome 21 in some cells.

How is DNA Testing For Down Syndrome Performed?

A blood sample is taken from the mother and submitted to a DNA testing lab. In a specialized DNA testing lab, the DNA is isolated from the maternal blood sample which contains a mixture of about 90% maternal and 10% fetal DNA. It is analyzed to check for an increased amount of genes present from a specific chromosome.

Who needs DNA Testing For Down Syndrome?

The American Congress of Obstetricians and Gynecologists recommends that the test be offered only to women at high risk of having children with aneuploidies (“aneuploidies” refers to the chromosome number being different from the usual number), including women ages 35 and over, those with abnormal ultrasound results or women who have given birth to children with Down syndrome.

It is important to note that DNA test for Down syndrome is a screening test that can help avoid invasive tests, but the results may still need to be confirmed with amniocentesis or chronic villus sampling by a DNA doctor.

Where Can You Get DNA Testing for Down Syndrome? 

Testing for Down syndrome can be performed at DNA testing centers. It is important to make sure that you choose a testing center that will provide confidentiality of information and of the DNA samples you provide.

When you are ready for DNA testing for a Down syndrome, please call us to schedule an appointment with the top DNA testing center in NYC.