GENETIC testing is revolutionising healthcare, offering individuals an unprecedented glimpse into their unique genetic makeup.
This is a medical test that analyses the changes or mutations in one’s genes, chromosomes, or proteins.
DNA is composed of base pairs represented by the letters A, T, C, and G, and contains biological instructions used in the development and functioning of all living organisms. Genes are segments of DNA.
Humans have about 20,000 to 25,000 genes in each cell containing biological instructions that may determine physical characteristics as well as a person’s risk of having or developing certain genetic disorders.
Genetic testing is hugely beneficial in helping doctors unravel crucial information about an individual’s risk of developing a particular genetic disorder or condition, and the possibility to pass it on to future offspring.
This tool not only aids in understanding the risk of hereditary diseases but may also provide insights into allergies, immune system characteristics and dietary preferences in order for personalised health and wellness.
Subang Jaya Medical Centre’s (SJMC) genetic counsellor Yoon Sook Yee explains the process involved in the genetic test.
After providing saliva or blood samples, the geneticist scrutinises the patient’s genes, picking certain gene markers that are of concern based on the individual’s medical history.
“If a patient has a family history of a certain cancer, the molecular geneticist reads the genes to identify changes in genetic coding, known as variants. The geneticist then interprets the possible inherited risks of cancers within this family.
“Advancements in technology, such as next generation sequencing, enable geneticists to read all the genes in one go, compared to older sequential methods.”
Yoon emphasises that genetic tests are used in various situations, from identifying suitable treatments for diagnosed diseases to assessing the risk of specific illnesses in seemingly healthy individuals.
For patients who have already been given a diagnosis of the disease, a genetic test may help suggest an optimum treatment.
The second scenario is individuals who may be at higher risk for specific illnesses. For these individuals, the focus of the test is about prevention and early detection.
“In the case of breast and ovarian cancer in women, for example, the BRCA1 and BRCA2 genes play a crucial role.
“These are also known as tumour suppressor genes and repair genetic mistakes in the cell. If they have variants that stop it from functioning well, they are unable to work as they should.
“So, women with the BRCA gene mutation are at higher risk of getting breast and ovarian cancer. In addition, men can also be carriers and have a higher risk of breast and prostate cancers, so it is not just a problem for women,” Yoon explains.
In these cases, the geneticist will know what genes to focus on based on the diseases in question.
There’s a third category of people who undergo genetic testing out of curiosity. As access to these tests becomes more viable, Yoon cautions individuals to be mindful of the purpose of the test and the information they receive from it.
Regardless of the reason for genetic testing, Yoon believes that genetic counselling should accompany any test.
She says that the genetic profile report may not be layman friendly; the topic of genes is also a complex and intricate field.
A genetic counsellor plays a crucial role in helping individuals understand the information derived from their genetic profile.
The counsellor breaks down complex genetic information and facilitates informed decision-making on the actions that best suit their profile.
“Counselling is important because we don’t want people to misunderstand that it is the end if they don’t have a particular genetic profile. Most diseases and risks are not only entirely dependent on genes.
“For example, while a certain contributing factor of type 2 diabetes is due to genetics, a much larger component is due to lifestyle choices.”
Transforming healthcare with precision medicine
With advanced techniques such as next generation sequencing, healthcare providers can do away with the ‘one-size-fits-all’ approach in medical treatments.
Traditionally, this means that doctors would make recommendations for treatment and disease prevention based on the average patient’s response.
This approach works well for some patients but not for others. Precision medicine is an innovative approach that customises healthcare to the individual, accounting for differences in genes, environments, and lifestyles.
Genetic testing will be used to select the most appropriate and optimal treatment.
SJMC’s consultant pathologist Prof Dr Pathmanathan Rajadurai comments on how genetic testing aids precision medicine.
“Genetic testing makes it possible for individualised and personalised medical treatment based on one’s genetic profile.
“It provides valuable information which may be used to design an optimum treatment plan. The information can assist in early disease detection, assessment of risk for hereditary conditions, and in validating causal relationships for modifiable risk factors in disease states,” he says.