Polymerase Chain Reaction in the Diagnosis of Uveitis

Abstract

Polymerase chain reaction (PCR) is a technique involving enzymatic amplification of nucleic acid sequences in repeated cycles of denaturation, oligonucleotide annealing, and DNA polymerase extension.1,2 The PCR uses in vitro enzymatic synthesis to amplify specific DNA sequences within a few hours. Since its inception in 1985, PCR has revolutionized research in the biologic sciences and medicine and has influenced criminology and law.3 The inventor of PCR, Kary Mullis, was awarded the Nobel Prize in Chemistry in 1993 in recognition of the extraordinary impact of PCR technology on scientific research.4,5 Polymerase chain reaction consists of repetitive cycles of specific DNA synthesis, defined by short stretches of preselected DNA. With each cycle, there is a doubling of the final, desired DNA product such that a million-fold amplification is possible.6 This powerful technique has numerous applications in diagnostic pathology, especially in the fields of microbiology, genetics, and oncology. Polymerase chain reaction has been used to diagnose uveitis, including viral uveitis, mycobacterial intraocular infections, infectious endophthalmitis, and protozoa eye diseases.7 However, the extremely high sensitivity of PCR can produce false-positive results, whereas its high specificity may produce false-negative results. These pitfalls can be minimized by techniques such as the use of both positive and negative controls, real-time PCR, and the performance of tests in an experienced laboratory. In any case, to ensure an accurate diagnosis, one must consider clinical data in the interpretation of a PCR result. We present diagnostic applications and examples of utilization of PCR in infectious and noninfectious uveitis, as well as in masquerade syndromes and other common ocular diseases with inflammatory components.