28.07.2010
10.1 Genetic information may come from many sources. These sources include a person’s family medical history, a clinical examination that diagnoses a genetic disorder, or a scientific test.
10.2 Scientific tests that reveal genetic information are of varying types.
Some genetic tests (here called DNA tests) directly analyse DNA or RNA. For example, testing of a genetic sequence may be undertaken by targeting a segment of DNA or RNA using a process known as polymerase chain reaction (PCR). This process, which was developed through the pioneering work of Kary Mullis and others at the Cetus Corporation in California in 1985 and led to the award of a Nobel Prize, enables the DNA from a single cell to be reproduced in large amounts (that is, amplified) for testing.[1]
Some tests do not analyse DNA or RNA material directly but test the biological products of particular genes. The measurement of certain proteins produced by genes, or certain metabolites, may reveal valuable information about gene function itself. For example, since the 1960s newborn screening programs have tested for phenylketonuria, galactosaemia and other genetic disorders. Some of these tests do not involve PCR analysis but still produce valuable genetic information.
Some routine biochemical tests of non-genetic substances may also reveal genetic information. For example, a positive test for high cholesterol or occult faecal blood may be the consequence of mutations in the genes conferring susceptibility to heart disease or colon cancer, respectively.[2] In an appropriate clinical setting, results of these biochemical tests may provide strong indicators of particular genetic disorders.
Some genetic diagnoses are made on the basis of the morphological characteristics of certain cells, tissues or at postmortem examination. Examples include the microscopic appearance of red blood cells in thalassaemia; the characteristic electro–microscopic appearances of the skin in epidermolysis bullosa, or the constellation of signs identified at postmortem in a foetus with skeletal dysplasia.[3]
Finally, some medical imaging processes reveal important genetic information. For example, nuchal translucency is an imaging procedure that is sometimes performed on a human foetus in utero. By measuring the presence of abnormal swelling under the skin at the back of the foetus’s neck, clinicians can predict a likelihood that the baby will have the genetic condition Down Syndrome.
10.3 During the course of the Inquiry different views emerged as to which of the five types of tests described above should properly be regarded as genetic tests. There was general agreement that the first and second categories (namely, the direct testing of genetic material and the testing of the biological products of genes) are appropriately described in this way. However, the status of the other three categories was contested. Some people appeared content to describe these tests as genetic tests; others took the view that they are non-genetic tests that may reveal genetic information.
10.4 The difference in description may assume importance in situations in which particular regulatory consequences flow from the classification of a test as genetic or non-genetic. For example, the peak body representing life insurers in Australia, the Investment and Financial Services Association, has developed a genetic testing policy for the industry, which regulates the use of genetic tests in underwriting life insurance products. For the purpose of the policy, a ‘genetic test’ is defined to mean
the direct analysis of DNA, RNA, genes or chromosomes for the purpose of determining inherited predisposition to a particular disease or group of diseases, but excluding DNA, RNA, gene or chromosome tests for acquired disease.[4]
10.5 This narrow definition corresponds most closely with the first category of tests described above. The effect is to leave a broad class of other tests, which are not covered by the industry policy and may therefore be dealt with in the traditional, and more liberal, fashion, despite the fact that they may reveal genetic information.
10.6 In many circumstances, however, this Inquiry is not concerned with the description of a particular test as genetic or otherwise. Rather it is concerned with the protection of genetic information, however it may be derived. For this reason, the Inquiry does not consider it necessary to propose a comprehensive definition of what a genetic test is. The Inquiry acknowledges that the direct testing of genetic samples and the testing of the biological products of genes form part of the core conception of genetic testing for the purpose of the Inquiry. Beyond this, much will depend on the context in which the question is asked. It is unlikely that the same answers will be given in the areas of medical research, clinical diagnosis, criminal investigation, or the many other circumstances in which genetic information may be sought and used.
[1] R Trent, Molecular Medicine: An Introductory Text (2nd ed, 1997) Churchill Livingstone, 19.
[2] J Beckwith and J Alper, ‘Reconsidering Genetic Anti-discrimination Legislation’ (1998) 26 Journal of Law, Medicine and Ethics 205, 207.
[3] M Buckley, Correspondence, 15 November 2002.
[4] See Investment and Financial Services Association, IFSA Standard 11.00 ‘Genetic Testing Policy’ (2002), IFSA.