What is genetic testing?

Genetic testing is the process of looking for changes in a gene (or even a chromosome or protein). These changes may result in diseases such as cancer. In this case the change is called a mutation.

Most genetic testing looks for mutations in DNA, the language of the genetic code. DNA can be obtained from a simple blood test and, in some circumstances, from saliva or a cheek swab. The costs of genetic testing are completely covered by your hospital in some cases.

The common types of genetic testing are described below.

Mutation Search

The first genetic test done in a family is called a “mutation search”. It is the most expensive, costing around $500 for one to 5 genes to over $1500 for a large panel. The search involves looking for spelling mistakes in the gene, or pieces added or removed, that mean the gene can’t do its job properly. This kind of testing is usually only done in an affected person (someone who has had a cancer) to increase the chances of finding a mutation.

Predictive Testing

When a mutation has been found, testing for this mistake can be offered to blood relatives. This is call predictive testing and is a “yes or no” kind of test: either the mutation is there, or it’s not. This kind of testing costs $200 to $400 and for some genes, such as BRCA1 and BRCA2, can be bulk billed.

Founder Mutations

Some groups of people have been isolated by geography, culture or religion. By chance, particular mutations are more common in some of these groups and are called Founder Mutations. This is a special type of Predictive testing. An example is testing for 3 specific mutations found in the BRCA1 and BRCA2 genes in people of Ashkenazi Jewish Heritage. This testing can be bulk billed if you have had breast or ovarian cancer.

Tumour Testing

Sometimes, testing the tumour itself can provide important clues as to whether the cancer was caused by a “faulty gene” that is being passed down through the family. Tumour testing can involve special stains or testing for genetic mutations in the cancer itself. It can also be used to guide treatment with targeted therapies.

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