Scientific breakthroughs in medicine have always changed the way people see health and the human body. But most of us tend to push the envelope when there’s a new understanding of health and disease.
When microbes were discovered, people thought every disease was infectious. When the genetic code and its influence on human health were revealed, people thought it would explain almost every disease.
Nowadays, we can see the shades of grey and understand that disease has many causes. They can be congenital and acquired, with a vast number of subtypes. Genetic disease is one of them, and it is not only a type of congenital disability.
Our genes can influence our susceptibility to specific ailments. But it is often a combination of genes and the environment that triggers the disease. For instance, we can have many people with type 2 diabetes in our family. But the risk of type 2 diabetes will be very low if we live a truly healthy lifestyle.
Based on this understanding, we’re covering in this article the topic of genetic testing. What is it about, and what is the actual reach of genetic testing to predict future disease?
What is genetic testing?
Genetic testing is a medical test that evaluates your genes against a series of variants. The goal is to detect a genetic condition passing down to you or specific genes predisposing you to certain diseases.
You can have different types of genetic testing procedures. They work for various purposes. For instance (1):
- Chromosome testing is the easiest genetic test because it only requires looking at the chromosomes to identify genetic changes. For example, a larger chromosome has double genetic material or an extra copy of a chromosome.
- Gene testing: We can go one step forward and identify gene variations in the DNA. These tests may analyze one part of the DNA or all of it. Gene testing is usually made to locate a specific set of genes instead of mapping all of them.
- Biochemical genetic testing: It is an alternative to the above. Instead of studying DNA, we would look for proteins coded by DNA and detect abnormalities. Proteins reflect DNA structure, but the results are not always accurate.
What genetic testing involves
Formal genetic testing is done in a laboratory and involves a complex and meticulous process. On the patient’s side, it only requires taking a sample. Depending on what the doctor is looking for, you could get a blood test done or take a sample from a cheek swab.
Amniotic fluid testing is a way to perform genetic testing on the fetus before birth. Other samples can be taken from the saliva, hair, or skin. Additionally, genetic testing can be performed in a prostate biopsy sample or any other type of cancer. This type of test detects congenital abnormalities in cancer to guide therapeutic measures.
Who should get genetic testing?
The most common type of genetic testing is prenatal testing. It should be performed in unborn babies if they are at a high risk of developing genetic abnormalities. It is also done in assisted reproduction to ensure that the embryos are fine before implanting them (2).
In adults, you can get tested to see if there’s a genetic disease you can pass down to your children. It is also helpful to evaluate if you’re at a higher risk of suffering from a type of disease or confirm a genetic disorder diagnosis.
Genetic testing is lately becoming very popular to find out what diseases you will suffer in the future. They can be direct-to-consumer genetic tests performed at home and sent to the provider. This approach can be inaccurate, and it is essential to be guided by a healthcare professional to avoid misunderstandings (3).
For example, in cancer, 5-10% of cases are related to genetic predisposition. Still, if you have a predisposition, it doesn’t mean you will develop cancer. You may never activate these genes if you’re not exposed to certain environmental elements. Thus, doctors would not run this type of test on every patient. They would only recommend this type of predictive genetic testing in patients with an established cancer trait in the family who is strongly suspected of carrying a cancer-related gene mutation (4,5).
Genetic testing to rule out hereditary cancer risk can be considered in these cases (4,5):
- If your closest family members have cancer (parents, siblings, children)
- If several family members on the same side were diagnosed with cancer in the same organ
- If a family member had two or more types of cancer simultaneously (especially in breast cancer, ovarian cancer, and other types of estrogen-dependent cancers.
- If a family member had a type of cancer that is known to have a strong hereditary link (hereditary cancer syndrome)
- When close family members develop cancer at a younger age than usual, especially in the case of genetic testing for prostate cancer risk (there’s a higher risk of metastatic prostate cancer in younger patients)
- If someone in your family had genetic testing before and turned out to be positive on a dangerous genetic mutation
Things to consider
It is essential to consider a few extra things before deciding on performing genetic testing:
- Remember that positive results in your genetic tests can be an emotional burden for you and your relatives. They may also need to perform the same test, and some of them might not be prepared for that type of information (6).
- Genetic testing is often expensive, and you need to consider the financial cost. Keep in mind that one positive test usually requires extra testing to see what’s going on. Talk to your doctor about this possibility to get your numbers straight.
- Not all insurance services cover this type of predictive test.
- Insurance companies and employers could use the results of your genetic tests to make employment and coverage decisions. To avoid that, some patients decide to pay for private genetic testing instead of getting any coverage (7).
- Home DNA testing procedures are not considered accurate by healthcare professionals. They often provide incorrect results. Thus, turn to genetic counseling if you’re serious about these tests or truly worried about inherited disease (3).
Screening prostate cancer risk with PSA testing is usually enough to detect metastatic disease. But sometimes, we are in a gray area, and the usual prostate cancer screening techniques are not enough. For instance, patients with a family history of aggressive prostate cancer or castration resistant prostate cancer may feel worried about carrying gene mutations that predispose to this disease. If you had cancer taken out, your doctor might also need to evaluate cancer cells to determine compromised genes.
In such instances, a genetic counselor is recommended to assess genetic risk and detect somatic mutations through a genetic test. This test can be performed on a blood sample or after a simple cheek swab. After taking out cancer, genetic testing is also available if needed.
Home testing is inaccurate, and formal genetic assessments of cancer risk are usually expensive. They may also require additional tests if you turn out to be positive. It is also important to remember that carrying a gene does not mean you will have cancer. If you follow instructions and live a healthy lifestyle, the risk may reduce dramatically.