Commentary
C1.2.1
Nucleic acid-based diagnosis of human disease arising from gene mutations falls into two major categories:a) germline inherited disorders (eg cystic fibrosis) or
b) somatic cell disorders (eg the bcr-abl translocation in leukaemia).
Inherited disorders
Standard
S1.2.1
In relation to human inherited disorders, laboratories must provide guidance (relevant for their particular community and circumstance) to the Level 1 and Level 2 grouping of DNA tests that they perform.Commentary
C1.2.2
DNA testing for inherited disorders has an added complexity compared with many other areas of laboratory testing because the information generated has relevance not only for the person being tested but also for other family members. Some DNA tests for human inherited disorders simply require the patient’s verbal consent after the provision of appropriate information by a qualified practitioner. For other DNA tests involving inherited disorders, however, formal pre and post-test professional genetic counselling, as well as formal written consent and additional confidentiality procedures, are appropriate parts of the testing process and are required for optimal patient care.C1.2.3
For the purpose of this document, a distinction is drawn between two broad classes of medical DNA testing for inherited genetic disorders, as shown in Table 1.1.Table 1.1 Levels of DNA testing
Type of DNA test for an inherited genetic disorder |
Explanatory notesa |
(standard) |
a) DNA testing for diagnostic purposes (eg the patient has clinical indicators or a family history of an established inherited disorder and DNA testing is being used to confirm the disorder) or any other DNA test that does not fall into level 2. b) Neonatal screening programs. |
(ie the test has the potential to lead to complex clinical issues) |
|
a The distinction between Level 1 (standard DNA test) and Level 2 (DNA test with potential complex issues) would usually be made by the doctor ordering the test, since that individual will be best placed to appreciate the short- term and long-term implications of the test for the patient and other family members.