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The science of genetic testing and its application in clinical practice has evolved rapidly over the last 20 years. As a result, today’s clinical laboratory can offer a wide expanse of various genetic tests that can be requested by a clinician. A recent study by the UnitedHealth Group’s Center for Health Reform and Modernization states that, as a nation, we spent over $5 billion on genetic testing in 2010 with that total potentially growing to somewhere between $15 billion and $25 billion by 2021. Not only are these tests growing in volume, but these tests are often the most expensive assays on a laboratory menu.
Ordering the appropriate genetic test for a patient can be complex, but is important from both a cost-savings and a patient-care standpoint. The Mayo Clinic Department of Laboratory Medicine and Pathology and Mayo Medical Laboratories employ genetic counselors to help clients navigate through the genetic testing ordering process. Genetic counselors are health care professionals who are educated in human medical genetics and trained in communicating genetic information. They are also skilled in interpreting family history information and identifying potential implications of genetic testing.
Genetic counselors at Mayo Clinic specialize in many areas of laboratory genetics, including Molecular Genetics, Cytogenetics, and Biochemical Genetics. A critical role for genetic counselors in each clinical laboratory is to evaluate the appropriateness of genetic testing. Mayo Clinic genetic counselors review many of the genetic test orders and reduce health care costs by ensuring the most appropriate test has been ordered. On average, the genetic counselors change or cancel approximately 8% of all reviewed genetic test orders. In addition, they help identify those patients who may need additional testing or who would benefit from time-sensitive therapies.
Genetic tests are misordered for a variety of reasons.
Diminished uroporphyrinogen I synthase activity can cause acute intermittent porphyria (AIP). AIP presents after puberty with pain crises and psychiatric symptoms.
Reduced uroporphyrinogen III synthase activity results in congenital erythropoietic porphyria (CEP). CEP typically presents in infancy with cutaneous findings, hemolytic anemia, and hepatosplenomegaly.
While these 2 conditions have a very different clinical presentation, the similarity of the enzyme names leads to frequent test misorders. By reviewing the patient’s age and the clinical information provided, the genetic counselors can identify most of these types of order mistakes. Performing the correct test ensures a more meaningful result for the patient and saves the patient, the health system, and the insurance provider time and money.
A mutation screening test is designed to identify a genetic mutation in a patient with clinical features of a disease.
A known mutation test is a targeted test for a specific mutation that has already been identified in an affected family member. Known mutation tests cannot be performed unless the familial mutation is provided to the laboratory. When a familial mutation is known, the known mutation test is a far less expensive and is a more direct approach to testing than performing a full mutation screen.
To illustrate, if an individual with colon cancer is suspected of having a MLH1 germline mutation (causative of Lynch syndrome), the mutation screen for the gene should be ordered. However, if a familial mutation in MLH1 has already been identified in a relative, then the known mutation test for MLH1 should be ordered, which costs approximately one-half that of a full mutation screening test.
Consider this situation: A congenital chromosome analysis is requested by a child’s pediatrician. Two years later the child is referred to a geneticist who orders another congenital chromosome study, as the geneticist had no knowledge that it was performed previously. In this case, the genetic counselor would identify this second, repeated, test as unnecessary and contact the clinician or client lab to determine if the previous result can be shared with this new request submitter. This effort improves patient care by providing important results to the provider currently caring for the patient and also reduces unnecessary health care spending.
Another situation that leads to duplicate testing is that some genetic tests are part of panels or other testing techniques, but are also orderable as separate tests. In the case of an infant presenting with cleft palate, a clinician may want to rule-out DiGeorge syndrome by fluorescence in situ hybridization (FISH) analysis of the 22q11.2 region. Given the nonspecific clinical findings, the clinician may also order an Array Comparative Genomic Hybridization (aCGH). The aCGH analysis covers the 22q11.2 region, rendering the FISH testing unnecessary. In these situations, if the stand-alone test and the panel or other testing method are both ordered, analysis of the same genetic region would be performed and charged twice. Genetic counselors attempt to identify these cases prior to analysis to avoid duplicate testing.
Each genetic laboratory has a slightly different approach to evaluating the appropriateness of testing but, in general, a thorough review of clinical history provided, patient’s age and gender, and previous genetic testing are used when assessing whether the order is appropriate. Based on this review, if the genetic counselors believe that a different test may be more appropriate for the patient, they will contact the client laboratory or ordering physician to discuss the clinical symptoms of the patient, the differential diagnosis, and what testing the ordering physician intended to order. The genetic counselors take all this information into consideration when they recommend what test or tests would be most appropriate for the patient.
The large repertoire of genetic testing services offered by Mayo Medical Laboratories can make selecting the appropriate test complicated. With the rapid growth of genomic medicine, testing options will only increase, further increasing this complexity. This multifarious nature has amplified the need for laboratory genetic counselors to assist clients with complex testing algorithms and the review of ordered tests for appropriateness to optimize patient care. Mayo Clinic’s laboratory genetic counselors are available to help physicians select the most appropriate tests for their patients and reduce unnecessary testing.
Claire Anderson, CGC
McKinsey Goodenberger, CGC
Katrina Kotzer, CGC
Kimberly Schahl, CGC