Saturday Genetics Quiz #34: DNA Test in the Laboratory

DNA tests are becoming more popular. Almost anyone with a bit of money can get one. But do you know what exactly goes on once you’ve submitted your sample to the laboratory?

This week’s genetics quiz question is:

What does the DNA lab do with your sample?

Answer with respect to paternity testing from DDC:

The sample collector sends the swabs to our laboratory in a sealed, tamper-evident package. When samples arrive in our laboratory, our staff checks to see if the package seal is intact. Each sample is recorded into our database. When all the samples for a paternity test case have arrived, we start the DNA test, which follows the following five steps:

1. Samples from each person are divided in two for Dual Process™. From this point on, two independent laboratory teams take the samples through the DNA testing process. DNA is extracted from the buccal swabs and purified.
2. The extracted DNA is added to a special chemical mix for the Polymerase Chain Reaction (PCR), a process that targets 16 specific locations in the DNA (called loci) and makes billions of copies of each location.
3. The products of PCR are analyzed to create a DNA profile, a genetic equivalent of a fingerprint for each tested party.
4. The child’s DNA profile is compared with the alleged father’s, and statistical analysis is performed to determine the probability of paternity. A 0% probability of paternity represents an exclusion (the alleged father is not the biological father) and at least a 99.99% probability represents an inclusion in a standard trio (the alleged father is the biological father).