DNA which contains the organism's genetic information is identical in all nucleated cells. Therefore, any tissue is suitable for genetic diagnosis e.g. DNA obtainable from a blood sample will enable testing for a wide range of genetic disorders such as abnomalities affecting the blood, brain, heart or liver. Moreover, since mutations associated with genetic diseases are transmitted from parents to offspring, the abnomalities in DNA are present at day 0 in an organism's development i.e. from the time of fertilisation. The advantages of DNA diagnosis over traditional approaches have meant that options such as carrier testing, presymptomatic diagnosis, prenatal diagnosis or population screening are increasingly becoming available to the community. The isolation of new genes, which is gathering momentum as the Human Genome Project progresses, will provide DNA markers for a wide range of human genetic disorders.
Challenges facing the community in the area of DNA genetic diagnosis are many.
These will include the increasing gap between what can be detected at the DNA level and the limited therapeutic options available e.g. the prenatal diagnosis scenario. The indications for DNA testing are the subject of much debate in the genetics and lay communities but will become even more complex when genes associated with multifactorial genetic disorders e.g. cancer, hypertension, dementia are identified. The issues of privacy and confidentiality have maintained a high profile in the present utilisation of DNA genetic diagnosis although it is to be hoped that familiarity does not breed contempt. The dilemma of unnecessary DNA testing which is facing the U.S. community has not been a problem in Australia in part because there is no Medicare rebate for DNA testing. However, the increasing trend to devolution of responsibility for medical decision-making has meant that services provided can be unplanned or dependent on local conditions or interest groups.