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Chapter 6 Personalized medicine


1.What is "personalized medicine" ?

As explained in the previous chapter, the genome type of each individual is different, therefore the nature of each human body is different from each other. In the near future, when genome typing or genomic diagnostics become popular, it would be possible to make a personalized medical treatment depending on the nature of individual person. This treatment is called "personalized medicine" (or tailor-made medicine).

Now, what is the personalized medicine? One good exmple is taking the case of purchasing clothes. If you want to purchase clothes for daily use, you may buy ready-made clothes. In this case, you can choose proper clothes depending on design, color, and size. Most of the ready-made clothes have wide range of selection to satisfy your needs.

However, on the special occasion like attending a ceremony or other formal meeting, you may want to wear a tailor-made suit suitable for such special occasion. In this case, you go to the tailor shop to have your own tailor-made suit according to your choice - your favored color, style, and fitting to your own size. The tailor may ask your choice of selection, measure your size, and give you a good advice.

As for ready-made clothes, the manufacture is aiming "the average needs of large population" based on the marketing. As for tailor-made suit, the tailor is aiming only "personal needs of a particular customer" based on the personal information.

In the current procedure of medical treatment, average population of the patients is targeted. Namely, every patient with similar symptoms can get the same medical treatment including drugs, regardless of individual genomic characteristics' differences.

On the contrary, in the case of personalized medicine, a patient is examined not only symptoms and diagnostics, but also the personal genomic information to identify the nature of patient's body. As a result, the patient is subject to the personalized medical treatment and is given the personalized drug prescription.

In particular, each person has different activity of drug metabolism due to the difference in the genome type of the metabolic enzyme. For instance, if a person has very weak enzyme activity, one can hardly metabolize the drug so that the drug concentration level in the blood remains high.

On the other hand, if a person has very strong enzyme activity, the drug disappears very quickly so that the drug concentration level in the blood would remain low. In other words, when several patients are given the same dose of drug, the actual effect of drug would differ depending on each individual's enzyme activity which is related to the genome type.

Based on the above concept, newly developed drugs are required to study the relations of the effectiveness of drug against the genome type, including the serious side effect due to the particular genome type.


2.What will be the change of medical treatment by the introduction of personalized medicine?

There will be a dramatic change in the concept of medical treatment including drug administration due to the introduction of personalized medicine. The new concept of personalized medicine will enforce the change of medical treatment from "treatment for averaged large population" to "treatment for individual person". The above change would result the following observations:

1) The medical treatment based on the patient's standpoint

The current medical treatment is focusing on the disease of patient to understand exactly the state and the cause of disease, in order to "choose" the most suitable medical treatment including drug administration.

However, in the personalized medicine, it is important for doctors to collect the personal information including the genome type, in order to understand the nature of the particular patient. Then the doctor will decide how he could provide the most suitable medical treatment for the particular patient. For this purpose, the doctor must obtain "informed consent" concerning the protection of personal information as well as providing medical treatment.

A face-to-face interview between the doctor and the patient should be conducted so that they can develop an intimate relationship and build mutual trust, and the doctor should understand the patient's status and nature clearly. In this way, the best medical treatment for the patient can be performed.

2) The "preventive" medical treatment

The current medical treatment is putting emphasis on "curing the disease", since the patient visits hospital after having a disease. However, in the future personalized medicine, when the information regarding the nature of the individual person is collected and analyzed, it could be possible to assess any potential risks of diseases (e.g. high blood pressure, stoke, cancer etc.). Based on the collected information, a new type of medical treatment to prevent these risks can be developed, which is called "preventive therapy".

This means that even though a person is identified with a potential risk of a particular disease based on the genomic examination, one could still have a chance to prevent the disease by performing the preventive therapy, designed based on the personal information. In the near future, the preventive therapy will become more important.

3) From large centralized hospital to local family doctor

The current medical treatment is performed mainly in a large centralized hospital focusing on "patients of the average population". This system is suitable for "curing the disease". However, in the case of personalized medicine, the current medical system may not be suitable. In particular, if a patient requires the personal medical treatment or the preventive therapy, a new system would be required to fulfill the needs. In future, a new system will be realized which combines a "family doctor" in the local town with a large centralized hospital.

In this system, the major role of family doctor is to establish mutual trust with individual patient and understand the characteristics of each person. On the other hand, the centralized hospital with an advanced medical treatment using the latest technologies and instruments deals with the patients who cannot be handled by family doctors.


3.From large centralized hospital to local family doctor

As stated before, human body is controlled by genomes, and proteins that are produced based on the information of genes. The functions of genomes are summarized as follows:

  • 1 Genome type
  • 2 Gene expression

Genome type is independent of time, and remains unchanged throughout the whole life. Therefore, it is called as "inherited constitution" (the original nature of our body) which is related to "potential risk of disease".

On the other hand, gene expression is dependent on time, and will change in time. Therefore, it is called as "acquired constitution" (the acquired nature of our body) which is related to "risk of acquired disease". In particular, as explained in the chapter 3 (epigenetics), even though one has inherited the potential risk of certain disease, if the switching of the corresponding gene would not occur, the disease would never be appeared.

This suggests that there will be a possibility of "preventing" the potential diseases by performing the preventive therapy. The "preventive therapy" means every possible therapy which could prevent or reduce the potential risk of disease, in particular, chronic disease.

In general, practical methods for preventive therapies could include such as food, nutrition, exercises, sports, non-smoking, non-alcohol, obesity prevention. In addition, mental therapies relating to mental and social behavior are also considered as the preventive therapy in a broad sense.

Why such preventive therapy can be effective? Because it focuses on the concept that "the inherited genome type cannot be changed, but the gene expression can be altered " At present, "switching" which is a key to explain the mechanism of gene expression is still under investigation in the epigenetic studies. If the preventive therapy is effective, it suggests that the gene expression profile has changed due to such therapy.

In future, when the preventive therapy becomes widely established, we can improve our quality of life as we can stay healthier. Instead of going to hospital after getting disease, we go to doctors to prevent getting sick. In addition, a large amount of money currently spent for the medical treatment will be drastically reduced.

Further readings:

1. T.A. Brown: " Genomes " BIOS Scientific Publishers Ltd. (1999)
2. Bryan M. Turner: Chromatin and Gene Regulation: Molecular Mechanisms in Epigenetics, Blackwell Science Ltd. (2001)
3. Eugene W. Nester et.al.: Microbiology: A human perspective McGraw-Hill (2007)
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  • Chapter 1 Genome and our body
  • Chapter 2 Gene expression and protein synthesis
  • Chapter 3 Mechanism of gene expression
  • Chapter 4 Genome type
  • Chapter 5 Genomic diagnostics
  • Chapter 6 Personalized medicine