Guide to genetic disorders

Genes carry instructions that tell your body how to work. They are found in almost every cell of your body.

Everyone has small variations (differences) in their genes. They are what make you unique.

Problems with your genes can cause health or development challenges.

Your genes are made of long chains of chemical compounds called deoxyribonucleic acid (DNA). Your DNA is found in the centre (nucleus) of all your cells, except your red blood cells.

A gene is a small section of DNA that codes for a particular protein. You have more than 20,000 genes within your DNA.

Long chains of DNA containing many genes are organised into chromosomes.

You have 2 copies of each chromosome. 23 chromosomes are passed down from each of your biological parents, making a total of 46 chromosomes.

Your genes influence your whole life from the moment you are conceived. They do this by telling your body to make proteins that are needed for your cells to work.

For example, these proteins can impact your health and wellbeing by:

• helping your cells grow, digest food and fight infections
• determining the colour of your eyes and blood type
• playing a part in your personality and how you think about the world

The way your genes work can be influenced by many different things, such as your lifestyle and the environment around you. This is called epigenetics.

A genetic disorder is a health condition that happens because of a problem with your gene or chromosome. These disorders can impact your development and health.

Some genetic disorders are obvious from birth, while others develop during childhood, adolescence or adulthood.

There are thousands of known genetic disorders that vary in their symptoms and severity.

As research continues, more genetic conditions caused by the interaction of your genes and environment (epigenetic disorders) are being identified.

Some genetic conditions happen more often in certain groups of people and in people with specific ancestry.

Gene mutation

A gene mutation is when there is a problem with a gene. Some gene mutations do not cause any health problems. However, some gene mutations can cause disorders such as: 

• cystic fibrosis
• Huntington's disease 
• haemophilia

Chromosome changes

Changes to the number or structure of chromosomes can cause genetic disorders, such as:

• Down syndrome — caused by an extra chromosome 
• Turner syndrome — caused by a missing chromosome
• Angelman syndrome — caused by a missing section or small part of a chromosome 

Gene mutations or changes in chromosomes that cause genetic disorders can happen for many different reasons:

• Random chance — a spontaneous mutation happens right before, during or after conception. When this happens, a child can have a genetic condition their parent doesn’t have.
• Inheritance — a gene mutation or chromosome change can be passed down from parent to child. Some conditions (known as 'recessive' disorders) are inherited because of a genetic mutation from both parents, while others (known as 'dominant') only need one copy of a changed gene from one of your parents.
• Changes to your DNA during your lifetime — for example, DNA damage caused by radiation from the sun can cause skin cancer to develop.

Reproductive carrier screening checks if you are a carrier of a genetic condition.

Having this test can help you understand your chances of having a child with a genetic condition. You might think about reproductive carrier screening if you are planning a pregnancy or are in early pregnancy.

There are Medicare rebates for the 3-gene carrier screen that tests for: 

• cystic fibrosis (Opens in new tab) 
• spinal muscular atrophy (SMA) 
• fragile X syndrome (Opens in new tab).

These rebates are available to everyone, even people without a personal history of symptoms or family history of these conditions. 

There is also an expanded carrier screening test that screens for other conditions, but this is not covered by Medicare. 

If you or your partner are interested in having reproductive carrier screening, ask your doctor for information and a referral.

Prenatal screening includes tests you can have during pregnancy to estimate the chance that your baby will be affected by certain genetic conditions.

Read more about prenatal screening (genetic screening in pregnancy) (Opens in new tab).

Genetic disorders are diagnosed by looking at the DNA in your cells. A laboratory can do this by testing your blood, saliva or your cells from the lining of your cheek.
If you are pregnant, your baby's DNA can be tested via amniocentesis (Opens in new tab) or chorionic villus sampling (CVS) (Opens in new tab).

Your doctor will recommend the right test for your situation.

Genetic testing can:

• diagnose you with a genetic condition
• check if you are likely to have a child with a genetic condition
• tell you if you have a higher chance of developing a particular condition
• tell you if you have a genetic condition that will start to cause symptoms later in life (known as pre-symptomatic genetic testing)

Some testing is available online or without the involvement of a health professional. The National Health and Medical Research Council (NHMRC) (Opens in new tab) warns that people should be cautious of direct-to-consumer tests (Opens in new tab).

Learn more about genetic testing.

Genetic counselling

If you are thinking about genetic testing, you should also think carefully about what the results might mean. Your test results can change how you feel about:

• yourself
• your health
• your future

They can also possibly affect your work conditions and your chances of getting insurance.

It's a good idea to start the process with your family doctor or a genetic counsellor.

A genetic counsellor is a highly trained professional whose job it is to discuss with you:

• the benefits and risks of testing
• privacy and confidentiality of your tests and results
• talking to members of your family about the testing
• potential work and insurance implications of genetic testing

Read more about genetic counselling (Opens in new tab).

Gene therapy is a type of medical treatment that aims to treat or prevent genetic conditions. Gene therapy works by putting the corrected gene into your cells to correct a mutation and restore normal cell function.

Gene therapy has already been used to treat diseases like haemophilia and spinal muscular atrophy (SMA).

Gene therapy is mostly still undergoing research and clinical trials and is not widely available in Australia.

If you or a family member has been diagnosed with a genetic condition, you may experience grief. Grief is a natural emotional response. Grief can affect your physical and mental health.

Remember, grief is a process. Everyone experiences and expresses their grief differently.

Read more about grief and loss.

To learn more about genetic disorders and services, you can visit NSW Centre for Genetics Education (Opens in new tab).

If you or someone you love is living with a genetic condition, you can visit Human Genetics Society of Australia's (Opens in new tab) 'Consumer Resources List (Opens in new tab)' webpage to find a list of support groups that meet in person or online.

If you want to seek advice about testing for a genetic disorder or preventing a disorder that runs in your family, go to the Australian Society for Genetic Counsellors (Opens in new tab) to find a genetic counsellor.

If you are pregnant or thinking about having a child, see Pregnancy, Birth and Baby's information on genetic counselling (Opens in new tab) or call the helpline on 1800 882 436.

Languages other than English

MotherSafe's Planning for a Healthy Pregnancy (Opens in new tab) is a fact sheet about general pregnancy planning as well as genetic testing and screening.