Genetic testing: What It Is and Why It Matters?

Genetic testing involves examining a person’s DNA to identify any changes. These changes, also known as mutations, if present, can indicate a genetic condition or an increased risk of developing one in the future. These genetic changes are usually hereditary.

However, the results of genetic testing are not always conclusive or straightforward, which can create undue confusion after the test. Understanding genetic testing and its significance can help individuals make informed decisions about going for testing and counselling and provide a clear idea of what to expect during the process.

This article explores genetic testing, including its purpose, methodology, types, and how to interpret the results.

What is Genetic Testing?

Genetic testing involves examining the DNA present in the body’s cells to identify any changes. Genetic testing looks for changes in the following:

1. Genes: A gene is a small section of DNA that contains instructions to control body functions. Genetic testing identifies changes in gene structure and any increased risk of diseases.
2. Chromosomes: A chromosome is a DNA structure carrying genes and genetic information. Genetic testing examines whole chromosomes and finds unusual changes, such as an extra copy or a missing chromosome.

There are different types of genetic testing, each serving a distinct purpose. These include:

1. Diagnostic Testing: This test identifies gene mutations to detect a genetic condition. For example, this testing can confirm the diagnosis of Huntington’s disease.
2. Presymptomatic Testing: This testing identifies if a person is likely to develop a disease before symptoms appear, especially in a case with a family history.
3. Carrier Testing: It determines whether a person carries a gene for an inherited disorder, even if they do not exhibit any symptoms of the disorder. It can be helpful for family planning or pregnancy.
4. Prenatal Testing: It looks for abnormalities in a baby’s genes or chromosomes as part of genetic disorder screening.
5. Newborn Testing: This testing is performed on newborns to detect genetic abnormalities that can cause certain disorders, such as phenylketonuria and initiate timely treatment.

Why is Genetic Testing Required?

Genetic testing is recommended by the doctors for the following reasons:

• To identify genetic disorders for early intervention and management.
• To confirm a genetic disorder based on symptoms, aiding in forming an effective treatment plan.
• To properly guide couples in understanding the risks of passing genetic conditions to their children.
• To tailor treatments based on the patient’s genetic makeup and severity of illness.

How is Genetic Testing Done?

Once an individual opts for genetic testing, usually after genetic counselling, the procedure typically involves the following steps:

• Test Selection: The doctor selects a specific test based on the patient’s family history, medical history, suspected condition, and presenting symptoms.
• Sample Collection: A sample of blood, saliva, hair, or sometimes skin cells are taken because they contain DNA that can be used to determine abnormalities.
• Testing: The sample is sent to an authorised lab for analysis, where gene mutations are examined through techniques such as PCR sequencing and microarray testing.
• Result Interpretation: The laboratory finalises the report and sends it to the doctor. The doctor communicates the results to the patient and discusses any further treatment options. This can be further followed by genetic counselling.

How to Interpret Genetic Testing Results?

Doctors interpret the results of genetic testing and determine the type of result that is obtained. There are three types of results as follows:

• Positive: A positive result means a genetic change was found. Depending on the purpose of the test, the positive result can confirm a diagnosis, indicate that the individual is a carrier of a specific genetic mutation, identify elevated risk of developing a disease (including cancer), or suggest further testing.
• Negative: A negative result means that no genetic changes were found, indicating that the person is not a carrier or does not have an elevated risk of developing a particular genetic disease. However, the doctor can recommend further testing or re-testing at a later date to confirm the negative result.
• Inconclusive: It means a genetic change is found, but its significance is not clear. The doctor can recommend testing affected or unaffected family members to clarify the result.

Genetic testing can provide valuable information regarding a genetic disorder or the risk of developing one in the future, enabling timely diagnosis and treatment. However, to determine whether genetic testing is required and of what type, genetic counselling is essential.

If an individual notices symptom or has family members with a genetic disorder, it is a good idea to consult a doctor and book a genetic counselling session at Dr Lal PathLabs via the Dr Lal PathLabs app.

FAQs

1. Is genetic testing during pregnancy safe?

Genetic testing for screening during pregnancy is usually safe. However, diagnostic genetic testing can present a small risk.

2. What is a DNA test?

A DNA test, also known as genetic testing, is used to determine any changes in the DNA which can indicate a genetic disorder.