The aims of this
learning module are:
- To learn about gene
discovery and biologic function of genes.
- To learn about Hardy
Weinberg equilibrium and how it can be used as a quality
control check.
- To illustrate how
multiplicative interactions can be characterized when a genetic and environmental
factor act at different points in a multi-step biologic
pathway.
- To
discuss the public health implications of gene-environment
interaction.
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Genomics and Cancer Prevention
Overview
This learning module is aimed
primarily at epidemiologists but could be adapted for discussion among public
health professionals.
Regular use of aspirin and other non-steroidal anti-inflammatory drugs reduces polyp recurrence and lowers the
risk of colon
cancer. But how do these drugs work? And who benefits from taking
them? Does everyone
benefit equally?
A recent paper by Martinez et al. sheds light on these questions, and provides fascinating insight into how genetic polymorphisms can help to uncover biologic mechanisms and establish benefit of public health interventions.
The authors provide evidence that the reduction in risk of polyp recurrence derived from taking aspirin may be greater in persons with a common variant in the ornithine decarboxylase gene (ODC). The ODC gene is a key enzyme involved in the biosynthesis of polyamines. And aspirin use is involved in the breakdown of polyamines. Thus, the ODC gene and aspirin use target a common metabolic pathway. The variant in the ODC gene influences how many polyamines are made, and aspirin influences how quickly polyamines are broken down. Since the ODC polymorphism and aspirin use act via different mechanisms on the same metabolic pathway, the effects may be synergistic.
This article presents a complex but very illustrative example of SNP discovery, functional genomics, and association studies. It raises important issues about the use of genetic information in public health practice.
A series of questions are posed, followed by some suggested answers.
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