About Genomics

What are genes?

Genes are the way that we inherit our characteristics.

We have between 20,000 and 25,000 genes in every cell of our bodies. Genes are made up of DNA. The information in our DNA is stored as a code made up of 4 bases: A, G, C and T.

Human DNA contains about 3 billion bases with more than 99% of those being the same in all people.

The order or sequence of these bases is as important as spelling a word or writing a sentence correctly.

Genes consist of coding (exonic) and non-coding (intronic) regions of DNA.

The coding regions are important to the production of the proteins that our genes make.

The non-coding regions of the DNA were initially thought to be less relevant, however more recently we are beginning to understand that this area of DNA also impacts on our genes.

What is a genetic variation?

Every person has two copies of each gene, one inherited from each parent. 

Most genes are the same in all people, but a small number of genes (fewer than one per cent) are slightly different between people.  These differences contribute to the uniqueness of a person, for example, height or hair colour.

While most variations in a person’s DNA do not have an effect on health, sometimes variations or “spelling mistakes” can mean that the gene where that variation occurred is no longer able to work correctly.  A condition caused by variations in one or more genes that disrupts normal development or causes a medical condition is called a genetic disorder.

What is genetic testing?

In genetic testing, the DNA sequence of a single gene is checked for changes that cause, or increase risk of developing a disease.

If a particular condition is linked to one or a couple of genes, genetic testing is a way to confirm or rule out the cause of the condition.

What is genomic testing?

Genomic testing, on the other hand, investigates many genes at the one time.  This is particularly useful when there are a number of genes which can cause a condition, or it is unknown which gene may be the cause.

There are a number of different tests which can be used to investigate the variations in multiple genes at the one time.

Panels are able to investigate a defined number of genes, for example a panel may contain 10 genes, or it may contain 400.

Whole Exome Sequencing is able to investigate the areas of DNA that code for protein (exonic DNA).

Whole Genome Sequencing is able to investigate our entire genomic DNA, that is the coding (exonic) and the non-coding (intronic) regions of our DNA.

Looking for more information on genes and genomic testing?

What is genomic medicine?

Genomic medicine, is the medical discipline that uses and applies genomic information as part of a patient’s clinical care – for medical management, and to help inform decisions of the patient and potentially their family.

In rare diseases, genomic medicine may be able to provide a diagnosis for a patient, while in cancer genomic medicine may be able to identify a heritable risk for cancer, or a targeted treatment for that particular cancer.