A genetic test involves the analysis of DNA, RNA, chromosomes, proteins, or other metabolites to detect changes related to an inheritable disorder. There are several different types of genetic testing:
- Direct testing involves the direct examination of a gene’s DNA or RNA code
- Linkage testing analyzes genetic markers co-inherited with a disease-causing gene
- Biochemical testing studies specific metabolites from samples such as blood or urine that can indicated whether a certain gene is functioning properly
- Cytogenetic testing involves examination of a cell’s chromosomes by a number of different methods
Although genetic testing shares some common features with other types of laboratory testing, in many ways it is unique. Genetic test results usually apply to the indivdual undergoing testing and to other family members. Conversely, sometimes other family members may need to be tested to clarify an individual’s testing result. During the early stages of gene discovery, research genetic testing may be available to families. This testing is done for the purpose of better understanding a genetic condition or gene, or for the development of a clinical test. Clinical tests are those in which specimens are examined and results are reported to the referring physician or patient for the purpose of diagnosis, prevention, or treatment. In the U.S., clinical laboratories must meet federal quality control and proficiency standards according to the Clinical Laboratory Improvement Ammendment of 1988 (CLIA).
The demand for genetic testing by genetics specialists, primary care physicians, and laypersons will continue to increase as more genes are discovered and new tests become availble. For investigators studying rare disorders, identification of a disease-causing gene can lead to new challenges, including identifying a CLIA-approved lab interested in transfering the test to a clinical setting, educating referring physicians and affected families about the availability of the new test, and confirming research molecular testing results in the clinical lab. The OHSU Biochemical Genetics Laboratory, Cytogenetics Laboratory, and Molecluar Diagnostic Center provide genetic testing for numerous disorders. The Molecular Diagnostic Center, led by Dr. Sue Richards, specializes in developing and providing testing for rare genetic disorders.