Here's an interesting article from the New York Times. There is no established legal precedent in Australia against the validity of a patent for a method of isolating a gene. On the other hand, the mere discovery of the gene would not be patentable.
Judge Invalidates Human Gene Patent - NYTimes.com
Somewhat related, our courts have held that there is no justification in law or logic to distinguish a process of curative treatment of the human body from that of cosmetic treatment, and that both of these forms of treatment may constitute a manner of manufacture (that is, proper subject matter) provided they have commercial application.