1. What Is Precision Medicine? Personalized Medicine Versus Precision Medicine (C. HIzel, P. Hamet, and J. Tremblay)
The push to appeal precision medicine for patient health care as individual approach received a major boost with the announcement of a $215 million for âPrecision Medicine Initiativeâ by President Obama earlier on January 2015 (www.whitehouse.gov/precision-medicine). There is a lot of overlap between the terms âPrecisionâ and âpersonalizedâ medicine and sometimes are used interchangeably with very subtle difference in life sciences. The more popularized term âprecision medicine,â emphasizes more the stratification of molecular-level information, whereas âpersonalized medicineâ is more defined with the ability to tailor treatments, as well as prevention strategies, to the unique characteristics of each person (Jameson and Longo, 2015; Mirnezami et al., 2012).
Even if with both terms genomic studies are one of the principal components for identifying the âAchilles heelâ of the subject affected by the disease, it is only one piece of the puzzle. Thereby, the creation of robust data from genomic risk to the âexposomeâ together with medical histories, social factors, and lifestyle factors is pivotal and they cannot act in isolation, but in concert to fulfill prior engagement of both terms (personalized/precision) in drug effectiveness and safety as much as in susceptibility to common multifactorial complex diseases for more precise personalized health care (Pashayan et al., 2011; Kittles, 2012). Like personalized medicine, precision medicine is neither parallel nor perpendicular! This is a highly interactive field that requires a synthesis in medicine, biochemistry, molecular biology, genetics, and even sociology and politics making a call to the informatics and biostatistics. That is to say, it is a matter of interdisciplinarity. Since the completion of Human Genome Project in 2003 symbolically announced the postgenomic era, determining the precise molecular structure of DNA and understanding the genome structure revolutionized our concept of health due to rapid development of molecular medicine specifically genetics, informatics, and other high-throughput technologies (e.g., nanotechnology, proteomics, metabolomics) which has led scientists and physicians to have an avant-garde thinking about how to detect and finally treat disease precisely (Naidoo et al., 2011). Upon the arrival of âpostgenomicsâ era medicine with the completion of the Human Genome Project (HGP) in 2003, an important conceptual shift is done on âprediction/preventionâ of future health outcomes (e.g., disease susceptibility, response to health interventions) with the use of individual genetic/genomics information. A corollary is that preventive and customized interventions and diagnostic tests may now be conceptualized (and in some cases implemented) during the presymptomatic phase of a disease or before pharmacotherapy is initiated (Hizel et al., 2009; Aydin Son et al., 2013). The concept of prevention represents the next step in the development of the âpredictive medicineâ as conceived by Jean Dausset, one of the three winners of the Nobel Prize in Physiology/Medicine in 1980. Dausset has suggested the term âpredictive medicineâ as a prerequisite step for preventive medicine. Subsequently in 1993, Jacques Ruffie offered a more comprehensive definition for the term and laid the philosophical basis for this new field in a book entitled âNaissance de la MĂ©decine PrĂ©dictiveâ (Birth of Predictive Medicine) (RuffiĂ©, 1993). Today, the term âpredictive medicineâ is replaced by one that is more precise: âpersonalized medicineâ and âprecision medicineâ enabled by the introduction and availability of high-throughput genomics technologies (Hizel et al., 2009; Aydin Son et al., 2013). As a consequence of genetic diversity and the existence of our genes in different forms in different environments with different lifestyles, the genetic basis of individual approach is resumed as âwe are all different,â which reflects the presence of genetic diversity (Cavalli-Sforza and Piazza, 1993; Cavalli-Sforza, 1997). Behind this expression, there is a scientific phenomenon called polymorphism. Our genes exist in different forms which determine the differences in âgene activity.â More than 93% of genes are polymorphic such as single nucleotide polymorphism (SNP) (Chakravarti, 2001). Polymorphism, especially SNP has the power to predict enzyme activity encoded by this or that gene. SNP detection enables us to understand better metabolic peculiarities in each case (Lai, 2001). So, precision medicine as a part of new genetics (Sutton, 1995) is based on the polymorphism phenomenon which now can be applied even in routine medical practice. In the light of new knowledge from genome studies and their by-products, matching molecular and genetic profiling with clinicalâpathological data is important to create precise individual approach in disease predisposition (âwho is at riskâ), diagnosis (âwhat is the causeâ), prognostic (âwho to treatâ), therapeutic response (âhow to treatâ) as treatment decision-making and prevention strategies in day-to-day personalized health care (Ginsburg and McCarthy, 2001; McCarthy et al., 2013). However, the activity of enzymes is not only under the control of genetic factors but also environmental factors which change gene activityâgene expression leading to different phenotypic expression for different diseases. Cells and tissue are in continuous communication across different interacting layers, such as DNA, RNA, and protein to maintain homeostasis and regulate biological processes in response to external environmental stimuli (Hausman et al., 2009). Accordingly, the main principle for the development of predictive and personalized/precision medicine as presented in Fig. 1.1, all of us âas open systemâ are the result of constant communication between our genes an...