text: PCR can be used to determine sex from a human DNA sample.  The loci of Alu element insertion is selected, amplified and evaluated in terms of size of the fragment. The sex assay utilizes AluSTXa for the X chromosome, AluSTYa for the Y chromosome, or both AluSTXa and AluSTYa, to reduce the possibility of error to a negligible quantity. The inserted chromosome yields a large fragment when the homologous region is amplified. The males are distinguished as having two DNA amplicons present, while females have only a single amplicon. The kit adapted for carrying out the method includes a pair of primers to amplify the locus and optionally polymerase chain reaction reagents.
  LCR can be used to diagnose tuberculosis. The sequence containing protein antigen B is targeted by four oligonucleotide primers—two for the sense strand, and two for the antisense strand. The primers bind adjacent to one another, forming a segment of double stranded DNA that once separated, can serve as a target for future rounds of replication. In this instance, the product can be detected via the microparticle enzyme immunoassay (MEIA).