Having blood drawn by a qualified medical professional is very safe. You’ll experience mild and momentary pain when the needle is inserted, and you may experience bruising at the needle insertion site after the test is complete. If you have an allergy to latex or to any adhesives, let the person know who’s drawing your blood so that any necessary adjustments can be made.
A blood sample is sent to a lab where a scientist analyzes the DNA in the blood, which contains genetic information. The scientist looks for information patterns within your DNA called “markers.” If someone has a particular marker known to be associated with a disease, that person should carry a specific gene. The presence of a gene that’s associated with a disease only indicates that the person being tested may be predisposed to have that disease. It doesn’t necessarily mean that the person will develop the disease