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The Genom of Homo sapiens.pdf

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362 MERIKANGASDay 1984; Ottman 1990; Hwang et al. 1994; Foppa andSpiegelman 1997; Yang and Khoury 1997; Khoury 1998;Garcia-Closas and Lubin 1999). <strong>The</strong>re is accumulatingevidence that gene–environment interaction will underliemany <strong>of</strong> the complex human diseases. Some examplesinclude inborn errors <strong>of</strong> metabolism, individual variationin response to drugs (Nebert et al. 1999), substance usedisorders (Dick et al. 2001; Heath et al. 2001), and theprotective influence <strong>of</strong> a deletion in the CC-chemokinereceptor gene on exposure to HIV (Michael 1999;Guttmacher and Collins 2002). Over the next decades, itwill be important to identify and evaluate the effects <strong>of</strong>specific environmental factors on disease outcomes andto refine measurement <strong>of</strong> environmental exposures toevaluate specificity <strong>of</strong> effects. Once susceptibility geneshave been identified, case-control studies defined by vulnerabilitygenotypes can be employed to identify environmentalfactors that lead to either the potentiation orsuppression <strong>of</strong> particular genotypes.Evidence for environmental factors can be gleanedfrom migration studies, a particularly powerful tool toidentify environmental exposures that may modify geneexpression. Migration studies have shown that the rates<strong>of</strong> breast cancer, heart disease, and type II diabetes haveincreased substantially in several subgroups who migratedto new cultural settings (Shaper and Elford 1991;Hanley et al. 1995; Trevisan et al. 1998).Intervention studies are another method to test environmentaletiology. Systematic trials <strong>of</strong> weight loss and exerciseamong high-risk <strong>of</strong>fspring <strong>of</strong> parents with type II diabeteshave shown a significant decrease in incidenceamong those in the weight loss group (Knoller et al. 2002).<strong>The</strong> increased incidence <strong>of</strong> type II diabetes among <strong>of</strong>fspringexposed prenatally to maternal diabetes also suggeststhat intrauterine exposure should be incorporatedinto genetic studies <strong>of</strong> this disorder (Sobngwi et al. 2003).ISSUES IN THE TRANSLATION OFGENOMICS TO THE PUBLICScientists, health care providers, ethicists, regulators,patient groups, and the pharmaceutical industry are challengedby the rapid changes in the science and technology<strong>of</strong> genetic research. Researchers and policymakers arecontinually updating and ensuring that they keep pacewith the rapidly evolving field by instilling ethicallysound, workable guidelines for both the research andclinical applications <strong>of</strong> human genetics. As a result <strong>of</strong> theincreased education, discussion, and understanding <strong>of</strong> therelevant issues, one area that will be particularly importantin genetic epidemiology research is informed consent.It is important to address consent issues in a reasoned,practical, and consistent way, including input frompatients and their families, health care providers, ethicists,scientists, regulatory bodies, research sponsors, andthe lay community. Responsibility for assessing issues relatedto family consent for research should remain withlocal investigators, ethics boards, and study sponsors. A“one-size-fits-all” perspective in the form <strong>of</strong> new regulations,for example, would likely be a disservice to all(Renegar et al. 2001). Specific issues that need to be consideredin applying genomics in the general populationinclude public comprehension <strong>of</strong> genetic information,confidentiality, and accurate risk estimation for complexdisorders.Confidentiality<strong>The</strong>re has been substantial attention to ethical issues aspart <strong>of</strong> the activities involved in mapping the humangenome (Human <strong>Genom</strong>e Project Information 2003:http://www.ornl.gov/sci/techresources/Human_<strong>Genom</strong>e/elsi/elsi.shtml). Principles <strong>of</strong> ethical research, confidentiality,and communication have been well-established.<strong>The</strong>re are several aspects <strong>of</strong> human subject protection thatdiffer when collecting DNA from samples <strong>of</strong> individualsrecruited from the general population compared with fromthe disease-based samples for which genetic counselinghas been most sought. With respect to complex disorders,and mental disorders in particular, several ethical issuesrequire attention including (1) protection <strong>of</strong> the privacy <strong>of</strong>the proband in the ascertainment process; (2) permissionto contact other family members; (3) specific problems associatedwith informed consent such as the ability <strong>of</strong> an individualin acute stages <strong>of</strong> illness to provide informed consent;and (4) therapeutic intervention (Alexander 2003).Successful and unsuccessful approaches that have beenapplied in ongoing population-based studies may ultimatelybe used to develop standards for the ethical application<strong>of</strong> genomics in general population samples.ComprehensionOne major impediment to the application <strong>of</strong> the tools <strong>of</strong>genomics to public health is a lack <strong>of</strong> public understanding<strong>of</strong> the implications <strong>of</strong> genetic markers. Althoughthere has been a dramatic increase in awareness <strong>of</strong> therole <strong>of</strong> genes in human behavior stemming from the accomplishmentsin genomics, some evidence suggests thatthere has not been a concomitant increase in public comprehension<strong>of</strong> the role <strong>of</strong> genes in disease etiology. Forexample, comparison <strong>of</strong> the results <strong>of</strong> a telephone surveyon basic principles <strong>of</strong> genetics for some common humandiseases administered in 1990 and 2000 showed no differencein accuracy between administration in 1990 and2000 (Institute for Social Research, University <strong>of</strong> Michigan)(Weiss 2003). Moreover, the public tends to attributefar more <strong>of</strong> the causality <strong>of</strong> human behavior andcomplex diseases to genes than warranted by empiricalevidence. As knowledge regarding specific roles <strong>of</strong> genesin complex diseases evolves, public education regardingrisk estimation will be critical in the translation <strong>of</strong> genomicsto public health.Risk Estimation for Complex Diseases<strong>The</strong> lack <strong>of</strong> knowledge regarding genes underlyingcomplex diseases reduces our ability to communicate ac-

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