For purposes of identity testing, there is no difference in DNA derived from buccal swabs or blood. However, non-DNA tests, such as HLA, are not run on buccal samples. The DNA testing performed is not affected by the DNA of bacteria, common foods, tobacco, or mother's milk. Good laboratory practices that incorporate exclusion confirmation, duplicate testing of independent specimen preparations, or require exclusions in different genetic systems, help prevent and detect mismatched specimens. No other tests are performed.
Genetic analysis is more complex than most physicians' office laboratories are capable of handling.
Traditional tests for red cell antigens and HLA cannot be used. DNA analysis will be successful depending on how the specimen was stored, the source of the specimen, and whether PCR-based tests are used. Current DNA technology requires that all parties be run at the same time in order to make appropriate reliable comparisons. Specimens collected earlier may not be available in the laboratory. In HLA testing, new antigens are defined on a regular basis, and the laboratories' ability to define various HLA antigens changes with time making it difficult to make comparisons with specimens collected at different times.