What are genes?

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

There are many variations in genes between people. They are what make you unique.

Problems with your genes can cause health or development challenges.

What are genes made of?

Genetic material is made of long chains of chemical compounds called deoxyribonucleic acid (DNA). Your DNA is found in the centre (nucleus) of all your 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 arranged into chromosomes.

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

How do genes influence my life?

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

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 field of knowledge is called epigenetics.

What is a genetic disorder?

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 health conditions caused by variations in your genes or chromosomes. Genetic disorders 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 that occur more frequently in specific groups of people and in people with particular 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 and haemophilia.

Chromosome changes

Changes to the number or structure of chromosomes can cause genetic disorders.

For examples, an extra chromosome can cause Down syndrome while a missing chromosome can cause Turner syndrome. Sometimes, only a section or small part of a chromosome is missing, for example in Angelman syndrome.

Why do genetic disorders occur?

Gene mutations or changes in chromosomes that cause genetic disorders can happen because of a number of different factors:

• Random chance — a spontaneous mutation happens right before, during or after conception. In this case, a child can have a genetic condition their parent does not have.
• Inheritance — a gene mutation or chromosome change can be passed down from parent to child. Some conditions (known as 'recessive' disorders) are inherited as a result of a genetic mutation from both parents, while others (known as 'dominant') require only one copy of a faulty gene from one of your parents.
• Changes to DNA during your lifetime — for example, radiation from the sun can damage your DNA in a way that allows skin cancer to develop.

What is reproductive carrier screening?

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

Testing can help you understand your chances of having a child with have a genetic condition. You might consider reproductive carrier screening if you are planning a pregnancy or are in early pregnancy.

As of 1 November 2023, Medicare rebates for reproductive carrier screening have been added. These new rebates are expected to help people find out their chance of having a child with some genetic conditions, such as cystic fibrosis, spinal muscular atrophy (SMA) or fragile X syndrome. These new rebates are available to everyone, even people without a personal history of symptoms or family history of these conditions. If you or your partner are interested in having reproductive carrier screening, ask your doctor for a referral.

What is prenatal screening?

Prenatal screening includes a range of tests you can have during pregnancy to estimate the risk that your pregnancy is affected by certain genetic conditions.

Read more about prenatal screening (genetic screening in pregnancy).

How are genetic disorders diagnosed?

Genetic disorders are diagnosed by looking at the DNA in your cells. A laboratory can do this by testing samples of body tissue including blood or cells from the lining of your cheek.

If you are pregnant, your baby's DNA can be tested via amniocentesis or chorionic villus sampling (CVS).

Your doctor will recommend the appropriate test for your situation.

Genetic testing can:

• diagnose you with a genetic condition
• check if you are at risk of having 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) warns that people should be cautious of this.

Learn more about genetic testing.

Genetic counselling

If you are considering genetic testing, you should think carefully about potential consequences of the results. Your test results can affect the way you feel about yourself, your health and your future. They can also potentially impact your work conditions and your chances of getting insurance.

For this reason, 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
• potential work and insurance implications of genetic testing

Read more about genetic counselling.

What is gene therapy?

Gene therapy is a type of medical treatment that aims to treat or prevent genetic conditions. Gene therapy works by delivering the corrected gene into your cells to correct a mutation and thereby restore normal 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 generally available in Australia.

Coping with a genetic disorder diagnosis

It you or your family member have been diagnosed with a genetic condition, you may experience grief. Grief is a natural emotional response. It 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.

Resources and support

• To learn more about genetic disorders and services, visit NSW Centre for Genetics Education.
• If you or someone you love is living with a genetic condition, you can visit Human Genetics Society of Australia's 'Consumer Resources List' webpage to find a list of support groups that meet in person or online.
• Find a genetic counsellor — 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 to find a genetic counsellor in your region.
• If you are pregnant or thinking about having a child, see Pregnancy, Birth and Baby's information on genetic counselling or call the helpline on 1800 882 436.

Do you prefer to read in languages other than English?

Genetic Alliance Australia has a brochure on genetic disorders in Arabic, Chinese and Korean.

MotherSafe's Planning for a Healthy Pregnancy is a fact sheet about general pregnancy planning as well as genetic testing and screening. It is also available in Arabic, Chinese, Bengali and Spanish.