To test DNA for determination of paternity and other family relationships, buccal swab samples are used almost exclusively as the source of the DNA. Buccal swabs are cheek cell samples that are collected by gently rubbing cotton swabs on the inside of the mouth. In the laboratory, DNA is extracted from the cheek cells on the swabs and then analyzed using sophisticated instrumentation to identify the donor’s genetic markers at specific chromosomal locations. Largely due to the fact that they are non-invasive and painless, buccal swabs replaced blood samples as the specimen of choice about 20 years ago. Today, blood samples are usually only tested if buccal swabs are unavailable. In the event that buccal swab or blood sampling is not possible, other types of samples may also be tested (see below).
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