The new millennium laboratory: molecular diagnostics goes clinical.

Applications of nucleic acid testing in most areas of the clinical laboratory have increased rapidly. The advantages of nucleic acid testing include enhanced specificity and sensitivity, ease of sample procurement, and more rapid turnaround time compared to conventional laboratory testing methods. However, the cost of testing is usually higher due to the need for additional laboratory space, specialized equipment, safety apparel, and the need for highly trained personnel. Most nucleic acid techniques currently used in a clinical setting can be categorized as either hybridization or amplification assays. Hybridization assays, including blotting techniques and microarrays, involve the complementary binding of an oligonucleotide probe of known DNA sequence with nucleic acid derived from the patient sample. To amplify small amounts of nucleic acid, assays such as the polymerase chain reaction and branched chain DNA employ either signal amplification or exponential amplification of target nucleic acid. Clinical applications of nucleic acid testing involve the detection of genetic diseases, e.g., sickle cell anemia and Huntington disease; and identification of infectious agents, e.g., HCV and HIV; or malignancies, e.g., chronic myelogenous leukemia and Burkitt lymphoma. Quantitative molecular assays also play important roles in predicting prognosis and monitoring responsiveness to therapy.