About half of the Australian population will be affected at some point in their life by a condition that is at least partly genetic in origin. Scientists estimate that more than 10, conditions are caused by changes in single genes.
Having a genetic susceptibility to a condition does not mean that you will develop the condition. It means that you are at increased risk of developing it if certain environmental factors, such as diet or exposure to chemicals, trigger its onset. If these triggering conditions do not occur, you may never develop the condition.
Some types of cancer are triggered by environmental factors such as diet and lifestyle. For example, prolonged exposure to the sun is linked to melanoma. Avoiding such triggers means significantly reducing the risks. Related parents are more likely than unrelated parents to have children with health problems or genetic conditions. This is because the two parents share one or more common ancestors and so carry some of the same genetic material.
If both partners carry the same inherited gene change, their children are more likely to have a genetic condition. Related couples are recommended to seek advice from a clinical genetics service if their family has a history of a genetic condition. If a family member has been diagnosed with a genetic condition, or if you know that a genetic condition runs in your family, it can be helpful to speak to a genetic counsellor.
Genetic counsellors are health professionals qualified in both counselling and genetics. As well as providing emotional support, they can help you to understand a genetic condition and what causes it, how it is inherited if it is , and what a diagnosis means for you and your family.
Genetic counsellors are trained to provide information and support that is sensitive to your family circumstances, culture and beliefs. Genetic services in Victoria provide genetic consultation, counselling, testing and diagnostic services for children, adults, families, and prospective parents. They also provide referral to community resources, including support groups, if needed. This page has been produced in consultation with and approved by:. The characteristic features of Angelman syndrome are not always obvious at birth, but develop during childhood.
Latest research suggests that most cancers are caused by environmental rather than genetic factors. Folic acid taken before conception, and during at least the first four weeks of pregnancy, can prevent around seven out of 10 cases of neural tube defects.
Charcot-Marie-Tooth disease is the most common inherited disorder affecting the peripheral nervous system. Most cleft palates and cleft lips can be repaired so that appearance and speech develop normally. Content on this website is provided for information purposes only. Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional.
The information and materials contained on this website are not intended to constitute a comprehensive guide concerning all aspects of the therapy, product or treatment described on the website. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions and to ascertain whether the particular therapy, service, product or treatment described on the website is suitable in their circumstances.
The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website. Skip to main content. Genetic conditions. Home Genetic conditions.
Genes and genetics explained. Actions for this page Listen Print. Summary Read the full fact sheet. On this page. Chromosomes How we inherit characteristics Dominant and recessive genes Co-dominant genes Gene changes in cells Genetic conditions Genes and genetics — related parents Genetic counselling and testing Where to get help. Chromosomes Humans typically have 46 chromosomes in each cell of their body, made up of 22 paired chromosomes and two sex chromosomes.
How we inherit characteristics Parents pass on traits or characteristics, such as eye colour and blood type, to their children through their genes. This results in two copies of every gene, which is composed of a variety of pairs of DNA.
Many genes come in different versions, called alleles. Alleles are differences in the DNA sequence of a gene. If you have two identical alleles, you are said to be homozygous for that gene whereas if you have two different alleles you're heterozygous. Some alleles are dominant, meaning that if you have one copy of that allele you will display that trait.
Other alleles are recessive, meaning you need two copies of that allele to display the trait. For example, Mendel took pea plants that were homozygous for different traits and crossbred them.
When crossing homozygous purple flowered plants to homozygous white flowered plants, the offspring which were heterozygous had purple flowers. The purple allele was dominant and the white one was recessive. When the heterozygous purple-flowered offspring were crossed with one another, some of their offspring would wind up with two copies of the recessive allele, giving them white flowers.
The more members of the family that are available, the better the results will be. Include all of the family members from whom you will be getting data. You can designate the males by a square and the females by a circle. Alternatively, you can do this activity with some members separately. Attached earlobes are clearly attached to the side of the head at the bottom of the earlobe whereas detached ones hang free.
There can be a range of attachment—just do your best to determine how attached the earlobes are. Do many relatives have the same type of earlobe or is there variation? Can you see how this trait was inherited? Write down your results in your "Earlobes" family tree.
A widow's peak is where the hairline comes to a V-shaped point above the person's forehead. Keep in mind that widow's peaks can vary considerably—when determining if a person has a widow's peak, count any sort of V-shaped hairline as a widow's peak. Do many relatives either have a widow's peak or don't have one? Write your results on your "Widow's Peak" family tree. For their research, scientists isolated four particular genes that affect the way a person perceives pain.
This is exciting news for people with chronic pain, as it could lead to a deeper understanding of the condition—and better ways to treat it. You probably know that traits like eye color, hair color, and earlobe shape are genetically inherited. However, according to the American Psychological Association , what you do with those features is also genetically determined.
That's right: You can thank mom and pop for your facial expressions. As Scientific American reported in , some people who were born blind—or were among a pair of siblings separated at birth—made similar facial expressions as their parents and other relatives despite never having learned them by sight.
Fun fact: Charles Darwin noticed the phenom a century ago. Some lucky folks experience a "runner's high" during or after exercise , which is caused by production of dopamine in the brain. These people can find other ways to derive pleasure from exercise by doing activities they enjoy, like swimming, rock climbing, or road biking—it just may be a bit more difficult to find biological motivation.
Is there a drug as entwined with American culture as caffeine? Some people just can't start their day without a cup of joe or four. Still, others just find it makes them feel jittery and anxious. In fact, according to a study in Psychopharmacology , scientists believe that genetics account for somewhere between 36 percent and 58 percent of the differences in the way people metabolize caffeine. The way your brain processes the chemicals adenosine and dopamine determines whether you'll experience insomnia, anxiety, or, in the worst case, withdrawal symptoms.
Having the right variant of the 5HT2A serotonin-receptor gene might make you more popular—at least, if you're a college-age male. People with the so-called "G variant" of this gene tend to be impulsive and break more rules, making them more popular with their peers. In , researchers at Michigan State University studied this phenomenon by having young men plan and throw parties.
According to the partygoers, the men with the G variant were considered more popular. Whether this applies to other demographics in other environments for example, where rule-breaking is not desirable has yet to be seen. For some people, procrastination feels as natural as eating, breathing, and sleeping—and it's something they may have picked up from mom and dad.
According to a study published in Psychological Science , nearly half of procrastination tendencies can be chalked up to genetics. What's more, according to a study also published in Psychological Science , those with a larger amygdala—the brain's emotional processing center, and something that by definition is passed down from your folks—were more likely to procrastinate. Age very well may be "just a number," but that doesn't mean the number is always accurate.
As it turns out, telomeres—that's the part of DNA on the tip of each chromosome—could dictate how old we look. According to a study published in Nature Genetics , in which scientists analyzed more than half a million telomeres, those with shorter tips looked, on average, three or four years older than those with normal-length tips. When it comes to deciding between candy and chocolate or chips and French fries, do you always pick the sweet option? If so, you likely inherited this trait from your parents.
In , Danish researchers found that people with a variation of the gene FGF21 have a practically incurable, insatiable sweet tooth.
They experience cravings and eat more sugar than other people, but they also tend to have less body fat. Sure, that sounds fantastic, but the news isn't all good: People with this genetic sweet tooth are reportedly more prone to high blood pressure.
Brussels sprouts, kale, hoppy beers, and dark chocolate all have a divisive bitterness to them. Chances are, you either love 'em or you hate 'em. If you're in the first camp, you may have a variation of the taste receptor gene TAS2R38 that makes your taste buds less sensitive to bitterness. The minority of the population—about a quarter, according to a report from NPR —has the version of TAS2R38 that makes them more sensitive to bitterness. Skiing and snowboarding can be risky sports—one wrong move and you could wind up with a concussion, a broken bone, or worse.
But the people who do them may be genetically predisposed to taking those risks. What's more, scientists think such folks might not process dopamine as efficiently as others, meaning that they need to take more risks to feel the same level of enjoyment.
Truly radical. It turns out that a sunny outlook on life may be an inherited trait. According to a study in the Proceedings of the National Academy Sciences , the gene that codes for oxytocin receptors—the cells in your brain that respond to the "love hormone"—displays some definite variations in people who are optimistic and have high self-esteem.
These people also reported feeling highly in control of their own lives. Still, it must be noted that there's rarely a percent correlation between a single gene and a complex personality trait, so this is just one piece of the personality puzzle. According to the same Proceedings of the National Academy Sciences study, those oxytocin receptors that help determine a person's optimism also help determine another positive personality trait: empathy.
These people have a variant of three particular genes that's a good predictor for altruism, prosocial behavior, and a greater ability to cope with stress.
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