CLS 420 Clinical Immunology & Molecular Diagnostics Molecular Diagnostics Module Introduction of Clinical Applications

Overview Molecular diagnostics provides sensitive/specific testing in: Infectious disease Oncology Genetics/Inherited diseases Human Identity This presentation will provide a very brief introduction to some of the clinical applications of molecular diagnostic testing. Applications are continually changing and expanding in the molecular diagnostics arena. This presentation will provide examples of the four areas listed on the slide.

Infectious Disease Testing Detection of non-culturable or difficult to culture organisms HIV Mycobacterium tuberculosis STIs: Neisseria gonorrhoeae/Chlamydia trachomatis HIV viral load assays are based on amplification of HIV RNA. The viral load is a quantitative test used to monitor a patient’s status and efficacy of antiviral treatment. Mycobacterium tuberculosis is a very slow growing organism. With conventional testing, final culture identification can take up to 12 weeks with susceptibility test results taking additional time. Today, upon growth, a possible M. tuberculosis organism can be identified with a DNA probe instead of conventional biochemicals decreasing the reporting time from weeks to days. Probes can be performed on an acid-fast smear positive sputum to detect the organism in the original specimen. The sexually transmitted infections of gonorrhea and chlamydia often coexist together. Both organisms are fastidious and can be difficult to culture in vitro. Commercial probe tests allow for the detection of one or both organism’s nucleic acid from a single swab. When testing for nucleic acid, organisms need not be viable (as opposed to culture).

Oncology Detection of genetic mutations/tumor markers B and T cell leukemia/lymphoma Breast, prostate, lung cancers Pharmacogenomics – determine efficacy of chemotherapy regimens based on individual’s genetic makeup (microarray analysis) Cancers are clonal. Most cancers appear to arise from a single, transformed cell as demonstrated by a variety of techniques ranging from cytogenetic analysis to DNA hybridization studies. Genetic alterations generally occur prior to clonal expansion so daughter cells comprising a tumor are genetically identical and each may harbor the same altered DNA, which then may serve as a tumor marker. Almost all cancers have been shown to contain genetic mutations. Some of these are presumably involved in the disease pathogenesis. These genetic mutations can include: DNA deletion, chromosomal translocation, gene amplification, viral insertion, and point mutations. These mutations alter the expression of genes involved in the regulation of cellular growth, cell division, differentiation, and other factors that affect the ability of cells to grow as a tumor, invade, and spread throughout the body. Pharmacogenomics – medicine is now able to predict, in some cases, whether a particular chemotherapy regimen will effectively treat a patient. In the past, it might be known that a particular drug would not be effective in 10% of cases, as an example. If there is a genetic understanding of why those 10% did not respond to the drug, microarray analysis can help identify that particular population prior to treatment failure.

Genetics/Inherited Diseases Examples: Cystic fibrosis Muscular Dystrophy Sickle cell anemia

Human Identity Forensic testing Paternity HLA genotyping/Transplantation