DNA paternity testing

DNA paternity testing is the use of DNA profiling (known as genetic fingerprinting) to determine whether two individuals are biologically parent and child. A paternity test establishes genetic proof whether a man is the biological father of an individual, and a maternity test establishes whether a woman is the biological mother of an individual. Tests can also determine the likelihood of someone being a biological grandparent to a grandchild. Though genetic testing is the most reliable standard, older methods also exist, including ABO blood group typing, analysis of various other proteins and enzymes, or using human leukocyte antigen antigens. The current techniques for paternity testing are using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). Paternity testing can now also be performed while the woman is still pregnant from a blood draw.

DNA testing is currently the most advanced and accurate technology to determine parentage. In a DNA parentage test, the result (called the 'probability of parentage) is 0% when the alleged parent is not biologically related to the child and the probability of parentage is typically 99.99% when the alleged parent is biologically related to the child. However, while almost all individuals have a single and distinct set of genes, rare individuals, known as "chimeras", have at least two different sets of genes, which can result in a false negative result if their reproductive tissue has a different genetic make-up from the tissue sampled for the test.

The testing is performed by collecting buccal cells found on the inside of a person's cheek using a buccal swab or cheek swab. These swabs have wooden or plastic stick handles with a cotton on synthetic tip. The collector rubs the inside of a person's cheek to collect as many buccal cells as possible. The buccal cells are then sent to a laboratory for testing. For paternity testing, samples from the alleged father and child would be needed. For maternity testing, samples from the alleged mother and child would be needed.

It is possible to determine who the biological father of the fetus is while the woman is still pregnant through procedures called chorionic villus sampling or amniocentesis. Choronic villus sampling (CVS) retrieves choronic villus (placental tissue) in either a transcervical or transabdominal manner. Amniocentesis retrieves amniotic fluid by inserting a needle through the pregnant mother's abdominal wall. These procedures are highly accurate because they are taking a sample directly from the fetus; however, there is a small risk for the woman to miscarry and lose the pregnancy as a result. Both CVS and Amnio require the pregnant woman to visit a genetic specialist known as a maternal fetal medicine specialist who will perform the procedure.

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