1. SECTIONS:
2. preface & acknowledgements
3. genetics at a glance
4. contacts, support & testing
5. testing & pregnancy
6. newborn screening
7. cancer in the family
8. cardiovascular conditions
9. chromosomal conditions
10. clotting & bleeding conditions
11. cystic fibrosis
12. diabetes
13. fragile X syndrome and other causes of developmental delay
14. haemoglobinopathies
15. hereditary haemochromatosis
16. neurofibromatosis
17. neurological conditions
18. psychiatric conditions
19. genetics in practice
20. emerging genetic technologies
21. glossary

Birth Defects Registers or Familial
Cancer Registers

 

1. Some States require mandatory notification of some abnormal genetic test results, identified in the first years of life by prenatal or postnatal testing.
2. See ‘Australian Genetics Services’ at the front of this section.
3. Registration with Familial Cancer Registries can assist patients and their families with appropriate testing information and management of surveillance as indicated by clinical or genetic testing.

 

Identification testing

 

1. DNA identification testing may be conducted in a number of contexts including:
2. Testing to confirm or deny the biological parentage of a person (parentage/paternity testing). The testing may be conducted, within or outside family law and child support proceedings, for an adopted child or a child born as a result of an artificial reproductive technology procedure involving donated gametes, seeking information about his or her biological parents
3. The identification of human remains
4. To establish of a member of a family for immigration purposes (kinship testing)
5. To determine ancestry.

 

Paternity (parentage) testing

1. DNA parentage testing has developed since the mid-1980s and is generally considered to be a more reliable form of testing than blood group testing. As with serological testing, it cannot definitively prove that a man is the biological father of a child but instead produces a probability of paternity.
2. It is assumed that the mother is the biological mother of the child, and that half of the child’s DNA has been inherited from her. The test is based on the identification of a series of DNA markers (STR – short tandem repeat sequences of DNA located in the non-coding regions of the DNA) that must have been inherited from the biological father. If the putative father does not carry all of the required DNA markers, he can be definitively excluded as the biological father of the child. If the putative father does carry all of these paternal markers, either he is the biological father of the child, or not the biological father but carries the genes by co-incidence.
3. As it is not possible to prove paternity absolutely, the result is then an estimation of the probability that the putative father is the biological father of the child and a paternity index (PI) is generated. This is a probability figure that compares the chance that the man is the father in the mother-child-father combination to the chance that the man was randomly chosen from the population. The PI will either exclude a man as the father or demonstrate that there is a high probability that he is the father of the child.
4. Using DNA profiles of all the people involved (mother, child and the two men who could be the father) a probability of being the father can be calculated for each of the possible fathers. A man can be excluded as the father if he does not match with the child on at least two STR loci. Inclusion as the father should preferably be associated with a 99.9% probability. Table 8 is an example of such a parentage test.
5. Parenting and kinship testing is not carried out in the public health system. Private laboratories conduct testing in Australia and provide DNA testing kits. Contact Genetics Services for information.
6. Where the testing is conducted for the purpose of family law proceedings, a regulatory framework governs the process. However, ‘private’ parentage testing is unregulated and offshore testing facilities via the Internet can also be accessed. So while parentage testing does not require the referral of a medical practitioner, if an opportunity arises to discuss issues relevant to using the commercial testing kits, important points include:
7. That it is essential that there is informed consent by both parents for a sample to be taken from a child
8. An exploration of whether the child is aware of the testing being undertaken, and discussing putting in place strategies for the child to gain an understanding of the reasons his or her parent is seeking the test and the possible impact of the test results on any existing relationships with that parent
9. An exploration of the consequences of the test for his or her relationship with the child or with the other parent
10. Understanding that the testing may take place when emotions are high and where parentage has been misattributed, perhaps for many years, there may be anger and grief.

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