Introduction: The Impact of Molecular Pathology on the Practice of Pathology

The success of the Human Genome Project 1 has expanded the field of molecular biology in an exponential manner. It has facilitated the identification of numerous novel genes of unknown function whose functions can now be determined and whose expressions can be monitored in different disease states. Whereas the discipline of pathology often refers to the rubric of the study of disease in general, molecular pathology refers to the analysis of nucleic acids and proteins to diagnose disease, predict the occurrence of disease, and predict the prognosis of diagnosed disease and guide therapy. Furthermore, recent advances in molecular pathology have positively affected the practice of medicine, especially diagnostic medicine. These changes result from abilities to clone disease-causing genes and the proteins that they encode and to detect the presence of these genes and proteins in the serum and other body fluids and tissues of patients, even though they may be present in minute quantities. This detection has been made possible by a veritable explosion of new, highly sensitive techniques involving amplification methods, such as polymerase chain reaction, branched DNA