Genetic Testing and Personalized Medicines


Traditional medical practice often applies the same treatments to all patients with the same disease, regardless of genetics and other contributing factors. However, this has many limitations as there are copious factors which contribute to disease, all which affect the effectiveness and safety of drugs.

Personalized medicine is an emerging form of treatment which aims to improve the specificity and effectiveness of medicine, by making it more targeted and individual to each patient.

One area of personalized medicine is called pharmacogenomics, which improves medications through genomic testing.

Technician with multipipette in genetic laboratory PCR research. Image Credit: Science Photo / Shutterstock

Technician with multipipette in genetic laboratory PCR research. Image Credit: Science Photo / Shutterstock

Why is Genetic Testing Useful Within Personalized Medicine Development?

Genes are used as the “blueprints” for protein production, used to dictate the sequence of amino acids which are transcribed from RNA sequences.

Investigation into genes can therefore inform researchers about each patient’s unique proteome. This provides many insights into disease and drug development, especially if a protein is involved in drug breakdown or drug transportation.

Additionally, a specific protein may be the target of the drug or involved in a drug-initiated signalling cascade. Therefore, analysis of genetic information plays a vital role within personalized medicine development.

Genetic testing has also identified that people with specific genetics also have similar responses to treatments. For example, people with a certain genetic variation may have a greater risk of side effects.

They may also require a much higher dose to obtain a beneficial effect, may not benefit at all from the treatment, may have a larger benefit to the treatment or may have a different optimal duration of treatment.

Therefore, by identifying which genetic variations are associated with these qualities, drugs and treatments can be improved, making them safer and more effective.

This area of research has already had a great deal of attention within many complex diseases, such as HIV, cancer, depression and lung disease.

How are Genomes Analysed?

To identify which genetic variations are associated with a specific disease or quality, a study is carried out called a “genome-wide association study”.

This study process involves the analysis of genomes from two different sets of individuals. The first set is a group which have the disease, and the second set is a group who do not have the disease. After their DNA is obtained, the genome is purified.

This is then adhered to chips and scanned via an automated process, identifying genetic markers called single nucleotide polymorphisms (SNPs).

SNPs that are more frequent in individuals with the disease, compared to those without the disease, suggests a genetic link called an association.

Such research is possible due to the completion of the Human Genome Project in 2003. This has given scientists many different research tools, such as a database containing the entire annotated human genome, a map of human genetic variations and the development of numerous technologies which are able to rapidly identify SNP variations.

All the identified associations are stored online, allowing scientists from around the world to access them and aid drug development. This has led to the identifications of variations which have contributed to many common disorders, such as mental illness, asthma and diabetes.

Another method used within the field of personalized medicine is disease risk assessment. Specific combinations of genes can increase susceptibility to a specific disease. Therefore, identification of disease-related SNPs can indicate a patient’s susceptibility to future diseases.

PCR is initially used to increase the amount of DNA taken from a sample, before the sequence is obtained via sequencing methods. Overall, identification of risk means that preventative medications and lifestyle changes can prevent the occurrence of a genetic disease all together.

Examples of Genomic Investigations

An example of personalized medicine which has been investigated is the use of warfarin for blood clots. These drugs work to thin your blood, however, the window of effective dosage is very narrow and different for each person.

Doctors aim to work out the highest amount which will successfully thin your blood, without leading to internal bleeding. This is usually assessed via analysis of many qualities, including age, weight and functionality of the kidney and liver. However, studies have now revealed that there are specific genetic variations associated with required dosage. Therefore, future use of personalized medicine may be able to assess the amount of required warfarin through genetic assessment, therefore making its use more effective and safe.

Future of Pharmacogenomics

Overall, personalized medicine has shown great potential uses. However, further development is required before it can be routinely used.

For example, assessment through clinical trials will be required to fully investigate the links of specific disease with genetic variations. However, there is a promising future, hoping to increase the effectiveness and safety of many types of medical treatment.

Reviewed by Chloe Barnett, BSc

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