Genetic testing and screening in Australia

 

Genetic information

 

  1. Genetic information may be obtained from:
  2. The examination of a person’s family medical history
  3. A clinical examination that diagnoses a genetic condition
  4. A genetic test
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Genetic tests

  1. There are several types of tests generally described as ‘genetic’ and include:
  2. Direct analysis of a genetic sequence where a segment of DNA or RNA is targeted using a process
    known as polymerase chain reaction (PCR). This process enables the DNA, even from a single cell,
    to be reproduced in large amounts (ie amplified) for testing (molecular genetic testing)
  3. Linkage testing (indirect gene tracking) when mutation(s) in a gene have not yet been defined
    or where the DNA region containing the gene is known but the gene itself has not been precisely
    located. This test involves tracking polymorphic markers located close to the gene in question
  4. Analysis of the chromosomes (cytogenetic testing). Molecular genetic techniques are increasingly
    used in cytogenetic analyses
  5. Analysis of the biological products of particular genes, eg: HbS in sickle cell disease
    (see Haemoglobinopathies); abnormal metabolites resulting from gene mutations such as high
    phenylalanine levels in phenylketonuria (PKU) in newborn screening (see Newborn screening);
    analysis of the protein produced by the BRCA gene (protein truncation testing – PTT) when testing
    for inherited predisposition to breast and ovarian cancer (see Cancer in the family)
  6. Biochemical tests of substances that may be under multifactorial control may also reveal genetic
    information. For example, a positive test for high cholesterol or faecal occult blood may be the
    consequence of mutations in the genes conferring susceptibility to heart disease or colon cancer.
    In an appropriate clinical setting, results of these biochemical tests may provide strong indicators
    of particular genetic conditions
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