GENOMIC PRECISION IN MEDICINE - REVOLUTIONIZING PERSONALIZED DISEASE PREVENTION AND TREATMENT

Medically Reviewed by Dr. Sony Sherpa, (MBBS) -  September 20, 2024

Over the last 30 years, the field of genetics and genomics has progressed by leaps and bounds, steering the advancement of healthcare toward the era of precision medicine. Genomic precision has revolutionized global understanding and expertise in disease prevention, diagnostics, treatment, and personalized medicine.

The following discussion explores what precision medicine and genomics are, as well as how they contribute towards revolutionizing the future of global healthcare.

What is Precision Medicine?

Precision medicine makes use of genomics in order to guide the healthcare process from prevention to diagnosis to treatment.^[1] Genomics enables specificity in genetic profiling and interactions, thus allowing the customization of healthcare services per individual needs with minimal error.

What is Genomics? Genomics refers to the study of the structure and function of genomes, which are the specific genetic sequences of organisms. Genetics and genomics differ in that genetics only analyses single genes, while genomics analyses whole gene sequences and their interactions, both amongst the genes present in the genome and with other genomes as well.^[2] In precision medicine, the interaction of the human genome with that of environmental factors, nutrients, pathogens, bacteria, plants, and animals all contribute towards the expression of either health or disease in varying degrees.

What is Personalized Medicine and How Does it Differ from Precision Medicine? Precision medicine is frequently used interchangeably with personalized medicine. However, personalized medicine is not the same as precision medicine. In personalized medicine, a standard treatment is modified to suit the individual needs of a patient, often with the intention of enhancing drug delivery or the patient’s ability to follow a protocol. Precision medicine aims to devise a treatment plan that is extremely specific to the patient, factoring in their genome, environmental exposures, diet, and lifestyle. A precision medicine protocol may still demand personalization to suit the patient’s needs,^[3] despite being extremely personalized in terms of genetics.

How Genomic Precision Medicine Has Transformed Prevention, Diagnosis, and Treatment for Good

Genomics currently rests at the forefront of medical research due to its high selectivity. It is now understood that patients with the same disease may convey completely unique genomes with several common underlying genetic themes. This understanding reveals how the conventional medical approach that offers a standard treatment for every person with the same diagnosis is flawed.

The Importance of Genes in Health. Genes are considered to hold the blueprints for creating cellular proteins, enzymes, and other products that enable cellular division, growth, and all other chemical processes to occur within the cell. Thus, the structure and function of a cell is dictated by what genes it possesses. Slight differences in familial genes give rise to different physical characteristics and other traits amongst people, which shape their unique physical requirements, metabolism, overall health, and disease susceptibility. Over and above hereditary genes, the genome interacts with the environment as well as other exposures, dietary input, and lifestyle factors. These lend themselves to promoting changes in the genome that may additionally influence health and disease by affecting the shape and functioning of cells and tissues. Through ascertaining a person's genetic sequence, precise information on the exact functioning of all tissues can be ascertained, as well as what might work to correct any imbalances.

Gene Mutations in Disease. Genomic changes that influence health can manifest in a number of different ways and are often referred to as gene mutations. They can occur as a result of DNA damage, replication errors, environmental factors, or pathogenic exposures.^[4] The most studied genetic mutations in the context of disease would be SNPs (single nucleotide polymorphisms), pronounced like ‘snips.’ As the name suggests, SNPs refer to changes in one nucleotide within a genetic sequence.^[5] Nucleotides are the building blocks of DNA (adenine, guanine, cytosine, thymine, and uracil), the order of which comprises the genome. SNPs may consist of a nucleotide that is missing or different from those found in the “normal” genetic sequence. Every person’s genome contains plenty of SNPs, most of which are neutral or quickly repaired. However, many SNPs can also contribute towards disease promotion.

How Genomic Sequencing in Precision Medicine Works. Studies in genomic medicine have highlighted collections of SNPs that are common to individuals with the same diagnosis, who may possess one or more of them. SNPs can also indicate whether someone is at a higher or lower risk for developing a disease. Besides mutations within genes, whole genes may be active (expressed) or inactive (silenced or suppressed), which may also contribute towards disease promotion or health. Both whole genes and SNPs can be switched on or off depending on our interactions with factors in the environment, diet, and lifestyle.

The Human Genome Project. Genomic precision medicine is currently centered around expanding and making use of findings from the Human Genome Project (HGP). With the launch of this project in the early 90s, our basic understanding of both health and disease has been revolutionized. This project originally aimed to analyze and sequence the entire human genome, which it managed to complete by 2004. It was revealed that the human genome comprises an average of 3.2 billion base pairs (nucleotides) that make up the distinct genetic sequences of every person. The HGP is still being expanded by new findings and genomic sequences pertaining to the nearly unfathomable number of genetic variations possible in the human genome. The project is now actively involved in mapping the full set of gene transcripts (transcriptome), human proteins (proteome), epigenetic functions, changes or adaptations (epigenome), and genome evolution that shows historical gene changes (comparative genomics). The project also attempts to find new ways of collecting and managing data (bioinformatics).

The Benefits of Genomic Precision Medicine

Precision medicine is being hailed as the future of healthcare, the benefits of which include:

• Accurate Diagnostics using Genomic Sequencing Technology. Genomic diagnostic tools take diagnosis to the next level by identifying disease subtypes that consist of distinct gene mutations and genomic interactions, which can give rise to the same disorder. This can be explained by the fact that there may be thousands of genes that encode for a single protein or enzyme, any number of which may be faulty or missing for a variety of reasons. This explains why one treatment does not necessarily work for all patients with the same disease and how precision medicine is a true game-changer in the future of healthcare.
• Multiple Precision Treatment Options. With the discovery of genomic differences among patients, novel precision treatment options that target disease genetic subtypes are becoming increasingly available. New classes of genomic drugs have been invented as a result that are capable of either promoting a gene (promoters), amplifying the gene’s function (enhancers or amplifiers), or switching a gene off (suppressors or repressors). Precision medicine also allows for gene-specific modifications to be made to the person’s diet and lifestyle, as well as alluding to environmental exposures that ought to be enhanced or avoided in order to complement therapy.
• Greatly Enhanced Personalization. While it may not always be the case, genomics in healthcare has the potential to greatly personalize medicine. Many of our personality and behavioral traits are coded into our genomes, which can reveal personal preferences, strengths, and weaknesses. When factoring in the entire genome of a patient, it will become increasingly possible to tailor therapy to accommodate their unique needs while tackling underlying genetic causes.
• Optimal Disease Prevention. Thanks to the sophistication of genetic sequencing, it is now possible to know years in advance which diseases one is at risk for and whether they are related to current lifestyle factors or familial genetics that increase the risk. Apart from helping one to prepare for aging, it also allows for an optimal prevention strategy to be implemented long before the onset of the predicted disease. This can substantially reduce the risk and potentially even prevent it from occurring at all.

Current Applications in Genomic Medicine

While genomics in healthcare has made significant advancements and contributions toward disease treatment and prevention, its current applications are still limited. These are summarized below.

Genomic Testing. Testing is now available in many developed countries where individuals merely send a sample of their genetic material (typically a saliva sample) to get tested. Most genetic testing is used to check for genetic disorders, including genetic muscle dystrophy disorders, cystic fibrosis, fragile X syndrome, or Down syndrome. Occasionally, genomic testing may be used to detect variations in cancer patients, such as BRCA1 and 2 gene mutations that increase the risk for breast and ovarian cancers. Several private companies are offering predictive genomic sequencing to the general public in order for them to assess their ancestral genetic makeup as well as to identify genes that place them at risk for developing certain age-related diseases. People can adjust their diets and lifestyles based on the findings of these tests in accordance with the latest research, which should ideally enhance their health and reduce their risk of developing diseases.^[6]

Gene-Specific Therapeutics. While there are hundreds of genomic therapeutics currently being investigated, only a small number have been approved for use. The FDA has put up a list of currently available genetic therapies, most of which aim to treat various cancers, collagen and cartilage defects, musculoskeletal atrophy, or rare genetic disorders, such as Cystic Fibrosis, Hemophilia B, and inherited retinal dystrophy (linked to a biallelic RPE65 mutation). The scope also includes therapies that can assist in bone marrow stem cell transplantation.

Drug Repurposing and Specificity. Another avenue that has recently opened thanks to genomic precision medicine would be drug specificity and repurposing. It has become evident that medications prescribed for specific conditions typically convey multiple effects on several bodily tissues and systems, over and above their intended scope of action. Examples include NSAIDs and chemo drugs with senotherapeutic properties. Genomic analysis is paving the way for practitioners to make better prescriptions by selecting medications that are highly compatible with the patient’s genomic profile. Additionally, it has allowed old drugs to be used for new purposes according to their genetic effects.

Current Limitations of Precision Medicine and Genomics

Despite major breakthroughs in precision medicine, more research, innovation, and development are required before it can be properly incorporated into healthcare. The main limitations with regard to genomics and precision medicine are highlighted below.

Ethnic Genetics. A review in 2021 has revealed that one of the main problems with current genomic precision medicine pertains to incomplete ethnic profiling. As much as 79% of genomic studies have centered around individuals of European descent, who only comprise roughly 16% of the global population.^[7] Efforts are being made to extend the growing evidence pool to other ethnic groups, as well as to include more research on indigenous people. Indigenous people can both benefit from and further the general understanding of health and wellness due to living lifestyles that are more akin to those of ancestral humans.

Gender-Based Genomic Medicine. While genomics has made great leaps and strides in terms of gender-based approaches in precision medicine, there is still much more work to be done. As with most of the scientific biological research to date, many experiments are still carried out on male genetic specimens, whether conducting investigations on single cells, tissues, or whole organisms. With the mapping of both the male and female human genome, genetic medicine has opened up many more avenues for promoting gender equality in medicine. Scientific and healthcare initiatives are currently striving for balanced studies and treatment between men and women, yet it may take several more years before gender-specific precision medicine is perfected and made available.

Affordability and Accessibility. One of the ultimate goals of genomic precision medicine is to make it available to the public in terms of affordability and accessibility. Certain types of precision medicine have already been deployed in top medical institutions as well as by private healthcare practitioners, yet their services are not available to most individuals. In the future, genomic sequencing technologies can eventually be made affordable to a wider range of healthcare providers, allowing the average patient to opt for genomic medicine and to be covered by medical aid. It is worth noting that precision medicine may not always be the most cost-effective option. In some cases, traditional treatments may be more effective and affordable.

Conclusion

With the completion of sequencing the full human genome in 2004, precision medicine has begun to grow at a rapid pace. Over the last couple of decades, genomic testing has uncovered specific gene mutations unique to distinct profiles of disease. This has greatly enhanced personalized medicine by revealing that there are likely to be several genomic profiles that give rise to any single diagnosis across patient populations. The future of healthcare can expect to see affordable genomic testing available to the public that allows practitioners to select gene-specific prevention and treatment options.

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