Cover of Human Genome Epidemiology: A Scientific Foundation for Using Genetic Information
to Improve Health and Prevent Disease
Human Genome Epidemiology is edited by three well-recognized experts in genetic
epidemiology, and their experience shows in the information and organization of this
text. While they do not define their intended audience, the material focuses on the
complexities of epidemiologic study and design in population-based genomics. Readability
characterizes all the chapters, and the concepts will be accessible to anyone with
a firm grounding in epidemiologic principles. Hence, the book will be useful for both
the graduate student and the experienced practitioner who wish to learn more about
this field.
The book contains four parts. Part One is devoted to the basics of common definitions,
molecular biology, and the laboratory testing that drove the Human Genome Project
and continue to be central in genomic research. Definitions include distinguishing
genetics (the study of single genes and their effects) from genomics (the study of
both single genes and the functions and interactions of all genes in the genome).
An example of the editors' thorough attention to detail is a chapter on the ethics
related to genomic studies.
Part Two is the most technical aspect of the text and examines the application of
standard epidemiologic research techniques in human genomics. These chapters discuss
additional research methods unique to human genome epidemiology and provide comprehensive
descriptions of the strengths and drawbacks of each research technique. The final
chapter in this section provides a checklist for designing and reporting genomic epidemiologic
studies. At this point, the average epidemiologist should have the information necessary
for assessing existing studies and perhaps designing credible original studies as
well.
How useful will the results of these studies prove to practical disease prevention? Part
Three explores three types of validity for human genetic tests. Analytic validity
is the sensitivity, specificity, and predictive value of a laboratory test for genotype.
Clinical validity refers to the same values with respect to phenotype; that is, is
a given test a good measure of gene–disease association? Last, clinical utility refers
to whether such tests provide information that can change disease outcomes. The remainder
of this section discusses the application of these concepts to clinical medicine,
pharmacology, and randomized clinical trials and offers guidelines for assessing these
values in different settings.
Part Three leaves the reader with a sense that while genetic testing may be useful
in clinical contexts or among select high-risk populations, there is little evidence
to support the use of most genetic tests in mass population testing. Part Four reinforces
this concept by providing 12 case studies on using human genome epidemiology to improve
health. In one example after another, reasonable evidence often supports an association
between a health outcome and a gene, a gene–gene interaction, or a gene–environment
interaction. But never does the evidence suggest that general population testing would
be an appropriate public health response.
One might infer that this text indicates a limited role for human genomic epidemiology
in current public health practice. However, the book does offer important points for
practical epidemiology. This is a rapidly growing field, and research epidemiologists
can play an essential role in designing and conducting research. In fact, we may learn
tomorrow of genetic tests with immediate general population applications. When such
reports do become available, it will be essential for epidemiologists to quickly grasp
the strengths and limitations of the interpreted studies. As genetic testing becomes
a high-profile public discussion, epidemiologists will need to provide policy makers
with a clear understanding of how to separate the wheat from the chaff in determining
public health actions. The editors note that the results of genomic epidemiologic
studies can be explored by other disciplines: policy (to decide value added), communication
(to explain risk information), economics (to examine cost effectiveness), and outcomes
research (to measure impact). For the most part, these aspects are not discussed in
this text, but public health professionals will need to address them all to use human
genomic epidemiology effectively in practice.