What is genomic medicine? An introduction to genetics in health care

Scientists and doctors have been studying genes and hereditary conditions (those handed down from parent to child) for many years. These days, it's possible for someone to have a genetic test for a number of illnesses. A blood sample is taken and closely examined for abnormal chromosomes, but because so much information is stored on the DNA, scientists only tend to look for particular disorders.

What is genomic medicine

Genomic medicine is the study of our genes (DNA) and their interaction with our health. Genomics investigates how a person’s biological information can be used to improve their clinical care and health outcomes (eg through effective diagnosis and personalised treatment.

While genetics looks at specific genes or groups of 'letters' along the DNA strand, genomics refers to the study of someone's entire genetic makeup. It's about how they relate and react with each other and is associated with conditions that have a broader range of triggers such as diabetes, heart disease, cancer and asthma.

How is genomics used in medicine?

• Diagnosis — for example, where the cause of a range of symptoms cannot be pinpointed by any other means.
  
• Prenatal tests that take place during pregnancy — either to screen (just in case something is wrong with the baby) or where there is already a family history. It helps the parents to make informed choices and plans for the future.
  
• Where there is a family history of serious genetic disorders, it can tell prospective parents whether or not they are a carrier and if they can pass it on to their children. It can also tell someone if they are likely to develop the inherited condition later in life, even if they don't yet have any symptoms.
  
• To assess risk — someone's genetic makeup can show their susceptibility to suffer certain illnesses, like heart disease, stroke, and cancer. Perhaps they're likely to have high cholesterol levels or to suffer problems with their veins. Possessing this knowledge means they can manage the risk through medicines, medical intervention, or making positive lifestyle changes.

The ways in which genomic medicine is making a difference

This greater understanding of the links between biology and disease brings benefits on several levels.

• Personal — each patient has medicines, treatment, and a health care plan tailored to them and their individual needs and risks. As an example, take the treatment of colorectal cancers. Some people with a particular gene mutation have better survival rates when treated with a non-steroidal anti-inflammatory, such as aspirin, than those without this mutation.¹
  
• Doctors — access to genomic information helps with diagnosis, managing treatments, and spotting symptoms across a wider cohort of patients. There have been a few cases where cerebral palsy diagnosis has been re-evaluated in the light of genetic testing, revealing a new diagnosis and, as a result, a new, effective treatment plan.²
  
• National level — developing strategies to care for rising trends and particular communities and programmes like newborn screening in the U.S., which examines for between 29 and 50 severe but treatable conditions.³
  
• On a world-wide scale — projects like the Online Mendelian Inheritance in Man⁴, an open-access database of all known human genetic conditions. This kind of approach means that the parents of children with rare syndromes are more likely to get the answers and the support they need.
  

What can I expect and what is genetic counselling?

There are a number of types of service provider. In the U.K., for example, the National Health Service employs 90 consultant clinical geneticists at 25 centres. They're supported by hundreds of specifically trained staff.⁵ Referral is usually through a general practitioner (GP or family doctor) and is available to those who are worried about a serious genetic family condition or a family tendency towards developing cancer, or to parents of a child with learning difficulties and other developmental problems looking for an expert assessment.

In places where a public service isn't available, or for those who choose to seek private health care treatment, check to make sure that the clinic you're using has the necessary registration (for example, in the UK this is through the Care Quality Commission, also known as the CQC⁶) and the lab is also correctly accredited.

Whatever the setting, the appointment might take some time and you may need to bring other members of your family with you. Your family and medical history will be mapped and explored, and it's likely you'll have a medical examination too. Finding out that there may be a life-changing or life-limiting condition in your future is a serious and, for some, traumatic experience. Alongside counselling, you may be offered tests (including blood tests)—with the option of having these done on the day or, if you need time to think about the possible implications, to come back at a later date.

Results can take weeks or even months to return (depending on the rarity of the genetic abnormality and how easy it is to find) but pre-natal test results will be returned much sooner.

Aftercare then depends on the results and the nature of what you're being tested for. Some people will be referred back to their family doctor along with full details, or they may go on to receive treatment at a specialist unit. Those who are aren't showing symptoms will be given support and advice about lifestyle changes, in order to minimise their risk, and advice about managing their potential condition in the future.

There are also a number of private companies who offer genetic testing by mail. It involves having a cheek swab or a blood sample taken at a local clinic. It's then sent off to the laboratory. The kinds of things tested for include genetic risk for diabetes and heart conditions, as well as ancestry information. Some companies deliver more of a service than others, with counsellors or other health professionals on hand to help. Convenient (but not necessarily cheap), it must be remembered that this is genetic testing without the usual level of holistic support found in established clinics.

The future

The broad area known as genomic medicine is evolving — the study of genetic mutation pathways and their variations is particularly exciting. But what does this mean for people on a practical level? As discussed earlier, there are some hereditary diseases that are difficult to diagnose simply because of the wide range of genes involved.

Scientists are working towards finding a chemical or genetic bottleneck for conditions like these. The ability to switch off a vital reaction along the pathway from genetic trigger to hay fever, dust allergy, or asthma, for example, would aid diagnosis and treatment, and possibly whether or not these traits need cause misery for the next generation.⁷

Epigenetics

The emerging field of epigenetics takes this idea one step further. It's based on the concept that each gene has its own chemical tag that tells the gene how to act. It is possible to turn the gene off (make it dormant) or turn it on (make it active) according to its chemical tag. In this way, the genetic code remains the same but the way in which it is expressed changes.⁸

This is a very exciting development. If things such as what we eat and drink and how much we sleep affect the way our genetic code manifests itself, what are the implications for disease and ageing? The times when genes are switched from a healthy, normal state into one that causes disease and the end of life?

These chemical modifications can also be passed on to the next generation, creating a more variable level to genetic inheritance. In other words, your lifestyle choices can affect your child’s health in a negative or positive way on a basic, biological level.

Time to think

Advances in genomic medicine mean that more diseases, both rare and more common, can be diagnosed and treated than ever before. But there are a few things to consider:

• Is our destiny in our genes? Depending on the genetic flaw, disease isn't always the outcome, and symptoms may delay or not manifest themselves at all. What checks are in place to guard against unfair discrimination and prejudice?
  
• With pre-implantation testing available to tell everything from the sex of an embryo through to specific genetic mutations, who makes the decision about which children get a chance at life?
  
• To what extent can doctors rely on genetic medicine for diagnosis and therapy? Could it lead to over-confidence, misdiagnosis or missed symptoms?
  
• How do governments and other policy-making authorities use information gathered by international genomic projects?
  

By understanding that which is already written down in our genetic code, we can predict and manage what happens in the future. New advances in genomic medicine create an environment where we can make sound health care plans, seek advice, and get treatment in the vital early stages of disease.

On a personal level, this doesn't stop at us — the principles behind epigenetics suggest that our everyday habits – what we eat and whether we smoke – can have a positive or negative effect on our grandchildren's biology, meaning that our genetic legacy is also well worth taking care of. At Aetna International, we may cover gene testing on a case by case basis, for example if an oncologist needs to determine the most suitable treatment for a member with cancer.

Read our article: How genetic information can support your family’s health: a guide.

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