Principles of the Polymerase Chain Reaction in Haematology

The polymerase chain reaction (PCR) is an automated process that specifically amplifies selected DNA sequences that are usually chosen to reflect the presence of genes, or parts of genes, in the sample material. Since many genetic alterations resulting in the onset of disease are now detectable using PCR, it can be used as both a diagnostic and prognostic tool. Genetic changes can occur in DNA due to mutation, deletion, inversion or chromosomal translocation. As a consequence, genes become either non functional or are aberrantly expressed. Research in recent years has now associated many defined genetic abnormalities with specific diseases. Therefore detection and surveillance of such lesions has led to disease diagnosis and subsequent monitoring of disease progression, for example, during and after administration of therapeutic regimens. The major effect of PCR in this area is that genetically abnormal cells can be detected within a normal cell population at a far lower incidence level than any other existing technology. Moreover, PCR can be used to identify naturally existing genetic polymorphisms that can be used as personal identifiers, or tags, for a given individual. Where these polymorphisms occur within a genetically modified region resulting in disease, identification of the polymorphism within families can be used as a predictor of disease carrier status or likelihood of inheritance of the disease.