The Human Genome Project: prospects for cardiology

Claude L’Enfant MDDirector, National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD

Geoffrey Pitt MD PhDBasic Life Science Research AssociateDepartment of Molecular and Cellular Physiology Stanford University, Stanford, CA

James Topper MD PhD Associate Professor of MedicineStanford University School of MedicineVice-President, COR TherapeuticsSouth San Francisco, CA

The Human Genome Project brings with it the prospect for significant advances in the field of cardiology.

The project will aid in:

1) the assessment of an individual’s susceptibility for disease

2) the evaluation of the progression and severity of many diseases (eg, heart failure)

3) further refinement in the field of pharmacogenetics.

Relevance to cardiology?

“As public health officials we have to be careful not to oversell this advance and opportunity. It will have tremendous yield, but not for tomorrow. Nor will it be of benefit to everybody.”

Claude L’Enfant MDDirector, National Heart, Lung and Blood Institute National Institutes of HealthBethesda, MD

Not to be oversold

The search for the genes responsible for a number of inheritable disease will be simplified.

While the Human Genome Project has been center-stage, a number of other organisms, such as the mouse and Drosophila, have had, or shortly will have, their genomes sequenced.

The compilation of both human and animal data will facilitate research considerably.

Research implications

The particular ion channel for the T-current, targeted by the antihypertensive and anti-anginal drug mibefradil, remained unidentified until comparable genomic data from the salmon were used to identify a variety of different ion channels.

The human gene corresponding to this channel has now been identified and channel function can now be studied in isolation.

Practical applications

Genes across species

Gene chip technology

Gene chip technology, or the microarray, allows researchers studying disease models to look at the expression of multiple genes at the same time - an area of research facilitated by human genome sequencing.

Image courtesy of Mitch Doktycz, Life Sciences Division, Oak Ridge National Laboratory and the Human Genome Program, U.S. Department of Energy. http://www.ornl.gov/hgmis.

The gene chip in practice

Using gene chips, researchers were able to look at more than 4000 genes in a rat infarct model setting.

They identified several hundred genes in 2 regions of the heart whose patterns changed dramatically in the several weeks after an infarct.

Looking at the expression of multiple genes is much more powerful than studying a single gene or protein at one time.

Stanton LW, Garrard LJ, Damm D, et al. Altered patterns of gene expression in response to myocardial infarction. Circ Res 2000:86;939-45.

Process of therapeutic development

The first stage in therapeutic development is to identify and evaluate a target. A validated target is a gene or protein whose function, when modulated, would have a positive impact on a disease process.

The second stage is to develop a therapeutic that modifies the target’s action (such as an antibody, receptor protein inhibitor, or small molecule).

The third stage is to test these therapies in clinical trials, first in normal human subjects, and then in the disease state.

The major impact of the Human Genome Project in therapeutic development will be to supply an enormous array of potential targets that will require validation.

A second impact of the project will be the use of genes in the natural variation of human populations to focus on potential therapeutics and clinical trials in specific risk groups (eg, hypertension).

Implications for therapeutic development

“Ultimately, what we hope to do results in pharmacogenomics - and that is, we will target specific drugs to exactly the specific patients who are most likely to benefit from them.”

James Topper MD PhD Associate Professor of MedicineStanford University School of MedicineVice-President, COR TherapeuticsSouth San Francisco, CA

Tailored therapeutics

Framingham for sale?

The Framingham phenotypic data will be a valuable asset when combined with the genotypic data of the participants. The study participants are key players in the issues surrounding these decisions.

This controversy highlights some of the political and social issues inherent to the Human Genome Project itself.

Framingham data

Broadly applicable principles regarding ownership of the Framingham data:

1) Access to this data should be free and equal. Ownership should not be limited to one company.

2) The data should at all times remain confidential.

3) Access to the data will be decided by committee whose university faculty members must remain free from conflict of interest.

Genomics and private ownership

Most genomic information should be publicly available, especially information derived from publicly funded sources.

For profit biotechnology and pharmaceutical companies are uniquely suited to develop beneficial therapeutics. Such economic incentives are not necessarily present at the academic level.

Intellectual property protection applies to the utility of this information if it may lead to therapeutic development.

A crucial balance

Private sector

Public good

Forthcoming studies

A significant number of epidemiological studies are now anticipated to exploit genetic stratification and risk, as opposed to the current methods of attributing environmental risk.

Many such studies looking at candidate genes derived from the human genome are expected to take place over the next 5-10 years, and will be extremely valuable.