Molecular medicine is a broad field includes the utilization of many molecular biological techniques for the analysis of diseases and their genetic aspects. Recombinant DNA and cloning techniques are used possibly for the study of disease genes. Molecular Medicine strives to promote the understanding of normal body functioning and disease pathogenesis at the molecular level and to allow researchers and physician-scientists to use that knowledge in the design of specific tools for disease diagnosis, treatment, prognosis, and prevention. Molecular medicine is the application of Molecular Biology and Molecular Genetics to the understanding of human health and disease. It aims to understand how health is maintained and the origins and mechanisms of human diseases. The advent of nucleic acid amplification and detection has resulted in a change from conventional laboratory methods that rely on phenotypic expression of antigens or biochemical products, to molecular methods for the rapid identification of a number of infectious agents. Molecular methods have become increasingly incorporated into the clinical microbiology laboratory, particularly for the detection and characterization of virus infections and for the diagnosis of diseases due to fastidious bacteria. Infection is one of the leading causes of human mortality and morbidity, with much of the burden falling on children. Infectious diseases are a major selective pressure, and the genes involved in the immune response are the most numerous and diverse in the human genome,6 indicating the evolutionary advantages of a varied immunological response to a wide range of infectious pathogens.