Regulation of Genetic Testing in Clinical Practice

Genetic testing is often regarded as a laboratory procedure in a molecular genetic laboratory. However, for practical use in health care, this definition is too narrow. In the majority of cases, the clinician is not using a genetic test for diagnostic purposes, but confirming or excluding a clinical suspicion of an underlying disorder of presumed genetic background. As an example, a confirmatory test could be requested by a pediatrician, who—after investigating an unhealthy child physically and with non-genetic tests—has the suspicion that the child has cystic fibrosis (CF) and orders a cystic fibrosis transmembrane conductance regulator (CFTR) mutation-scan. If mutations are found, the diagnosis is confirmed. Furthermore, the specific mutations detected may give prognostic information about the child’s future health. The doctor will also have information that can be used for family investigations, and possibly for prenatal diagnosis. However, if only one or no mutations are found, this does not exclude the possibility that the child has CF. The test used may not detect all mutations, or the gene may have been silenced by other reasons—e.g., altering the regulation of the gene. An example of exclusion testing is a patient presenting with neurological symptoms, leading to a suspicion of Huntington’s disease. A genetic test revealing a normal set of trinucleotide repeats in the IT-15 gene will indicate that the symptoms are not caused by this disorder. In genetic testing, the information given to the patients and their families must be an integral part of the process.