Genetic epidemiology

Genetic epidemiology is the study of the role of genetic factors in determining health and disease in families and in populations, and the interplay of such genetic factors with environmental factors. In slightly more formal language, genetic epidemiology was defined by Morton as "a science which deals with the etiology, distribution, and control of disease in groups of relatives and with inherited causes of disease in populations". It is closely allied to both molecular epidemiology and statistical genetics, but these overlapping fields each have distinct emphases, societies and journals.

Traditionally, the study of the role of genetics in disease progresses through the following study designs, each answering a slightly different question:

• Familial aggregation studies: Is there a genetic component to the disease, and what are the relative contributions of genes and environment?
• Segregation studies: What is the pattern of inheritance of the disease (e.g. dominant or recessive)?
• Linkage studies: On which part of which chromosome is the disease gene located?
• Association studies: Which allele of which gene is associated with the disease?

This traditional approach has proved highly successful in identifying monogenic disorders and locating the genes responsible.

More recently, the scope of genetic epidemiology has expanded to include common diseases for which many genes each make a smaller contribution (polygenic, multifactorial or multigenic disorders). This has developed rapidly in the first decade of the 21st century following completion of the Human Genome Project, as advances in genotyping technology and associated reductions in cost has made it feasible to conduct large-scale genome-wide association studies that genotype many thousands of single nucleotide polymorphisms in thousands of individuals. These have led to the discovery of many genetic polymorphisms that influence the risk of developing many common diseases.

Hemimelia or longitudinal fibular deficiency

Genotoxicity bioindicator

Cluster analysis in epidemiology is the method for identifying wide spread population damage (as mercury contamination in Minamata Bay) but a genotoxicity bioindicator is a preventive way of seeing congenital malformations epidemic in human populations.

A biological monitor, or biomonitor, is defined as an organism that provides quantitative information on the quality of the environment around it. Therefore, a good biomonitor will indicate the presence of the pollutant and also attempt to provide additional information about the amount and intensity of the exposure.

Endocrine Disruption (feminization); Reproductive Failure causes include early embryonic death, embryo toxicity and abnormal parental behaviour during incubation; Eggshell Thinning including Double-crested Cormorants, Ospreys, Bald Eagles, Black-crowned Night-Herons and Herring Gulls, maybe are caused by pollution or another genotoxic factor.

Malformed frogs are caused by parasites, genetic disease or pollution? Crossed bills, jaw defects, extra limbs, and malformed feet, joints and eyes were found in Herring Gulls and at least eight other species of fish-eating waterbirds from great lakes, malformed frogs were found in Minnesota. (see external link below)

See also

• Thalidomide
• Genetic disorder
• Molecular epidemiology
• Mutation
• Radiation damage
• Population genetics
• Hardy–Weinberg principle
• Population groups in biomedicine

Further reading

• Khoury, M.J.; Beaty, T.H.; Cohen, B.H. (1993). Fundamentals of genetic epidemiology. New York: Oxford University Press. ISBN 0195052889. 
• Morton, Newton E; Chung, Chin Sik, eds. (1978). Genetic Epidemiology. New York: Academic Press. ISBN 0-12-508050-6 
• Morton, N.E (1997). "Genetic Epidemiology". Annals of Human Genetics 61 (1): 1–13. doi:10.1017/S0003480096005891. http://linkage.rockefeller.edu/wli/reading/morton97.pdf. Retrieved 15 June 2010 
• Khoury, Muin J.; Little, Julian; Burke, Wylie, eds. (2003). Human Genome Epidemiology: A scientific foundation for using genetic information to improve health and prevent disease. Oxford University Press. ISBN 978-0-19-514674-5. http://www.oup.com/uk/catalogue/?ci=9780195146745. 
• Spence, M. A. (2005). "Genetic Epidemiology". Encyclopedia of Biostatistics. Wiley Interscience. doi:10.1002/0470011815.b2a05034. 
• Thomas, D.C. (2004). Statistical Methods in Genetic Epidemiology. Oxford University Press. ISBN 019515939X. http://www.oup.com/uk/catalogue/?ci=9780195159394. 

• Teare, M.D. (2011). Genetic Epidemiology. Springer. ISBN 978-1-60327-415-9. 

External links

• Genetic Epidemiology (journal)
• International Genetic Epidemiology Society

• Journal of Joint Bone Surgery 1997 Jan;79(1):58-65.
• North American Reporting Center for Amphibian Malformations (NARCAM) Jul. 2011
• Minnesota's Malformed Frogs Jul. 2011
• Studies offer new insights into causes of deformed frogs Jul. 2011
• Deformed Frogs Raise Concerns Jul. 2011
• Deformed Frog Pictures Jul. 2011
• Contaminant-related effects observed in Herring Gulls and other fish-eating waterbirds inhabiting the Great Lakes.