Deck 28: Special Topics 4 Genomics and Personalized Medicine

Question 1

In this chapter, we present three case studies that use personalized genomics analysis to predict and treat diseases. Although these cases have shown how personalized medicine may evolve in the future, they have triggered controversy. What are some objections to these types of studies, and how can these objections be addressed?

Answer 1

Personalized medicine will evolve in the future but there are still many technical hurdles which are still to be sorted out. Some of them are as follows:
i. Each personal genome generates vast amount of information which must be stored in databases.
ii. For this analysis, data from large scale population genotyping studies linking sequence variants to phenotype, disease or drug responses needs to be gathered.
iii. DNA profiling, microarray analysis and SNP detection requires to be more cheap, accurate and faster.
There are many social implications of personalized medicine such as:
i. Even before disease and symptomscosts of genetic tests, genetic counseling has to be reimbursed by insurance companies.
ii. Regulatory changes are required to ensure that genetic tests and genomic sequencing are accurate and patient's privacy is guaranteed.
iii. The data generated have to be reliably stored in databases..
iv. Costs involved in the development of genomics and personalized medicines are disputed topics and treated as misallocation of resources and money.
v. Highly specialized and expensive medical care will be unavailable to poor people.
To address these problems these solutions can be undertaken:
i. Efficient automated systems and algorithms need to be developed to deal with massive amount of information.
ii. More user friendly databases and softwares need to be developed.
iii. Their needs to be the development of more health care providers which will use electronic health records.
iv. More efficient health records which will store the information and protect and will help the health care provider to retrieve it easily.
v. More genetic counselors and genomic specialists are required.

Question 2

What is pharmacogenomics, and how does it differ from pharmacogenetics?

Answer 2

Pharmacogenomics involves the study of how the genetic composition of an individual regulates the body's response to drugs. This field of study is considered to be the most developed area of personalized medicine. One of the biggest advantage of this field is that it reduces the risk of side effects as well as allows for more better use of treatments.
Pharmacogenetics on the other hand involves the study of how an individual's drug responses are influenced by sequence variations within a specific gene of that individual. This term is many times used interchangeably with that of Pharmacogenomics.
From the definitions it can be seen that a very minor difference exists between the two terms. Pharmacogenomics is a broader term which encompasses the study of influence of all the genes in response to a drug whereas pharmacogenetics is a narrow term restricting the study of effect of sequence variations within genes in response to a drug. Also, in pharmacogenomics, various other viewpoints are taken into consideration like drug metabolism aspects and how these aspects are affected by genetic traits. A lot of genes and different genetic polymorphisms like Single Nucleotide Polymorphisms (SNPs) can affect an individual's response to a drug as many interactions take place between a drug and proteins in the body of the patient.

Question 3

What are the biggest challenges that must be overcome before personalized medicine becomes a routine component of medical care? What do you think is the most difficult of these challenges and why?

Answer 3

Progress of personalized medicine in recent years ensures development of more personalized therapies in near future. However, there are some challenges that must be overcome before personalized medicine becomes a routine component of medical care.
Here is the list of some of those challenges:
a) The wide gap between data collection and interpretation of complex interactions needs to be filled appropriately.
b) Effective, accurate and reliable therapies that are cheaper and have less side effects have to be developed, since personalized medicine is dependent on these therapies.
c) There is need for the development of automated health information technologies.
d) There is need to use electronic health records to store, retrieve and analyze each patient's genomic profile which is not fully possible in today's scenario.
e) Regulatory changes are required so that genetic tests and genomic sequencing are accurate and reliable.
All these challenges need to be sorted out. However, developing therapies for rare and less rewarding diseases is the most difficult challenge because of the complexity of the living systems.

Question 4

Describe how the drug Herceptin works. What types of gene tests are ordered prior to treatment with Herceptin?

Question 5

How can we ensure that a patient's privacy is maintained as genome information accumulates within medical records? How would you feel about allowing your genome sequence to be available for use in research?

Question 6

What is the Oncotype DX Assay, and how is it used?

Question 7

As gene tests and genomic sequences become more commonplace, how can we prevent the emergence of "genetic discrimination" in employment and medical insurance?

Question 8

How do the cytochrome P450 proteins affect drug responses? Give two examples.

Question 9

What types of genetic tests are currently available, and how are they classified?

Question 10

Give two examples of how genomic studies have altered our understanding of cancers.

Question 11

Why is it necessary to examine gene-expression profiles, in addition to genome sequencing, for effective personalized medicine?

Question 12

Using the PharmGKB database, explain the relationship between CYP2D6 variants and the response of patients to the breast cancer drug, tamoxifen.