Molecular Diagnostics in Clinical Laboratory Medicine
Molecular diagnostics is a collective term used to describe methods that provide precise findings about nucleic acids (DNA and RNA). The molecular diagnostic field has grown tremendously since the completion of the Human Genome Project, which provided the scientific community with the human genome sequence, as well as the genomic sequences of bacteria, viruses, and many other organisms. Advances in instrumentation technology, such as the automation of polymerase chain reaction (PCR), enabled the new genotype and subsequent phenotype information to be used in clinical diagnostics. Clinical genetics, molecular pathology, infectious disease, cancer diagnostics, and immunological testing have all experienced enormous growth and change as a result of molecular techniques.
PCR is essential in identifying variants and mutations in the human genome that cause disease or variation to treatment. Over 120 inherited primary immunodeficiency diseases are known to result from genetic abnormalities. Recent advances in molecular diagnostics have made it possible to detect mutations in the genes responsible for many of these diseases. Clinical genetic testing detects the underlying genetic cause of hereditary diseases, such as cystic fibrosis, Tay Sach's disease, Huntington's disease, and sickle cell anemia. Increasingly, the association between genetics and environmental factors is being studied in susceptibility to chronic diseases like diabetes and hypertension. Molecular pathology focuses on somatic mutations, or changes to one's DNA after birth. Patients with chronic myelogenous leukemia have a chromosomal translocation between the 9th and the 22nd chromosomes, which is now detectable by PCR as opposed to conventional cytogenetic methods that are laborious and time consuming. Pharmacogenomic testing allows physicians to predict patient response to certain drug therapy based on the individual's genotype. This allows for individually tailored drug regimens, reduced adverse drug reactions, and needless expenditure of valuable health care resources.
The specificity and sensitivity of PCR have dramatically changed the practice of infectious disease testing. One of many examples is the detection of tuberculosis, which previously required 6 to 8 weeks of culturing, but can now be detected in hours using molecular testing. Pathogens that cannot be cultured can presently be identified by PCR. Genotyping tests for HIV and hepatitis C allow physicians to make informed therapeutic choices for the patient based on the infecting virus' specific genetic information.
Viracor-IBT is highly skilled in the application of molecular techniques to infectious disease and immunological testing. Many of our infectious disease assays are built on the principle of highly automated, real-time quantitative PCR. Real-time PCR refers to the detection of the pathogen while amplification is occurring instead of following completion of amplification, as in the case of conventional PCR. While at first glance this may not seem significant, the method allows for quantification of the pathogen, also known as viral load monitoring, thus enabling physicians to track the level of virus in a patient over a period of time. Viral load information, coupled with a fast turnaround time for results, allows physicians to assess the severity of infection and adjust drug therapy regimens based on patient progress, an advancement that has become critical to outcomes in managing immunocompromised patients.