Where are genes made of?
Almost every cell in your body has a centre called a nucleus. In almost every nucleus, there are 46 chromosomes. Chromosomes are passed from parent to child, and are the vehicle for carrying all that you inherit from your parents.
Chromosomes are made of a chemical compound called DNA (deoxyribose nucleic acid). A gene is a small section of that DNA. You have more than 20,000 genes in you.
How do genes influence your life?
Genes contain the recipes for who you are, and they influence your life from the moment you are conceived. They have a strong influence over how you look and the colour of your eyes, hair and skin.
But genes don't switch off the moment you're born. They also play a part in your personality and how you think about the world. They continue to influence your health and wellbeing for as long as you live.
They do this by instructing the body to produce the proteins that are used by cells. These proteins will help you to do things such as grow, digest food and think. Some will help protect you against cancer, while others will allow cancer to grow.
The way your genes work can be influenced by many different things, such as your way of life or the environment around you. This field of knowledge is known as epigenetics.
What's a genetic disorder?
A genetic disorder is a health condition that comes about because of a problem with a gene or with a chromosome.
A problem with a single gene is known as a gene mutation. You can have a gene mutation without it causing any problems. But some gene mutations can cause problems, for example cystic fibrosis, Huntington's disease and haemophilia.
If you have a problem with a chromosome, that will probably cause noticeable problems. Some people have a missing chromosome, some have an extra chromosome, some have a broken chromosome. Down syndrome, Turner syndrome and Kleinfelter syndrome are all examples of chromosomal disorders.
Why do genetic disorders occur?
Most genetic disorders occur by chance. Genes and chromosomes are complex, and they often get changed slightly in the formation of new life.
Some disorders are passed down from a parent. If a parent has a damaged gene or chromosome, and that is passed down to a child, the child's health might be affected.
Still others come about through changes in a person's DNA during their life. For example, radiation from the sun can damage a person's DNA in a way that it allows skin cancer to develop.
Are genetic disorders always inherited?
Many genetic disorders are inherited, but many others are not. Some occur simply because a piece of genetic material was damaged as it was being passed from parent to child. In that case, a child can have a genetic disorder that the parent does not have. The damage to the gene is known as a spontaneous mutation.
Do they always show up in babies?
No. Some genetic conditions can be seen from birth. Others show up during childhood, adolescence or adult life.
What about testing for genetic disorders?
Some genetic disorders can be tested for. There are many issues to consider before having genetic testing, such as the effect of a test on other family members or whether having a test might affect your working conditions or your chances of getting insurance. You should not have genetic testing without thinking it through carefully.
If you want to discuss testing, it is worth starting with your family doctor or a genetic counsellor. A genetic counsellor is an expert in working with families to discuss genetic conditions. They can talk to you about whether testing is available, the benefits and risks of testing, about privacy and confidentiality, about work and insurance, and about talking to members of your family. They generally work with other experts in genetics.
Some testing is available online or without the involvement of a health professional. The National Health and Medical Research Council warns that people should be cautious of this.
Learn more about genetic testing.
Where to go for help?
If you want to try to prevent genetic disorders that run in your family, or if you want to try to detect any possible genetic conditions, it is best to talk to either your doctor or a genetic counsellor. To find a genetic counsellor, go to the Australian Society for Genetic Counsellors.
If you have a genetic condition in your family, there are many support groups you can join. Some meet in person while others operate online or by telephone. You can find some listed by the Human Genetics Society of Australia, and you can find others by searching for the condition you are concerned with.
The NSW Centre for Genetics Education is a good source of more detailed information on genetic disorders and services.
If you're 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.
If you or someone you care for has a rare genetic condition, you may be able to find a support group through Genetic Alliance Australia.
Last reviewed: August 2016