How is Screening Done?
A blood or saliva sample is collected and sent to a genetics laboratory for DNA analysis. Certain locations on the DNA chain are examined for mutations that are known to be linked to specific genetic conditions.
After several weeks, a report is available that shows whether or not the individual has the mutations linked to particular diseases in a given population. The report should be carefully read by a knowledgeable doctor or trained genetic counselor, and you should keep our report in an easily-accessible location, both to know your results, and to be certain of which diseases were included in the screening.
A screening report is not a simple yes/no situation. It will tell the doctor or genetics specialist what the chances are that the patient is a carrier of a particular disease based on the mutations tested for, but there is always a residual risk that the patient has an unidentified mutation and may still be a carrier.
Note on Tay-Sachs: Previously, the recommendation for Tay-Sachs screening was a combination of DNA and biochemical carrier screening (enzyme analysis), in which a saliva test would be followed up by a blood test. This recommendation has been updated; either a saliva test or a blood test are now equally valid for Tay-Sachs screening. Click here for statement from the National Tay Sachs and Allied Diseases Foundation (NTSAD).
For more information on the screening process, watch the video A Genetic Counselor on Screening.
