Speaking Notes

PDM 5324

November 17, 2009

Chapter 16 -- Identifying the Roles of Genetic and Environmental Factors in Disease Causation

It would be a mistake to assume that environmental EXPOSURES ALONE are the cause of human diseases.

It is clear that genetics (heredity) affect how individuals react to exposures.

To my knowledge, public health in the United States is not associated with eugenics, which efforts may have good intentions but have historically bad associations.

On the other hand, couples often seek information regarding how to help assure that their future children will be born with genes that will predispose them to long and healthy lives.

A result of the human genome project will be an increasing emphasis on the creation of designer drugs intended to be of value to individuals having certain genetic properties.

http://en.wikipedia.org/wiki/Human_Genome_Project

The most recent "revolution" in science has been computer technology. The next revolution will almost certainly be a revolution in biology, followed by a merging of technology and biology.

The ETHICAL and POLITICAL implications are huge as we gradually draw closer to designing and even creating living beings.

Epidemiologists would be remiss not to include an understanding of genetics into their efforts to understand and address the causes of diseases.

It became evident long ago that when persons closely related have children together the children may have problems of genetic origins. Beyond discouraging incest the measures public officials may take to prevent children being born with genes that predispose them to conditions or diseases are controversial.

This chapter is not about PUBLIC POLICY but rather is about including genetic considerations as factors (similar to exposures) in order to understand the origins of diseases in individuals and populations.

HERIDITY and ENVIRONMENT clearly both contribute to the incidence of diseases in individuals (and to personal behaviors, values and personalities). Environment tends to REINFORCE the affects of heredity in that most children are raised by biological parents or other close relatives.

Some diseases and conditions are known to have DIRECT GENETIC ORIGINS. Down syndrome is an example.

Some other diseases and conditions have been observed to be associated with genetic origins, including some forms of cancer.

The incidence rates of some other diseases appear to be driven by a combination of a genes plus the presence of some other disease. (see page 266.)

I am unsure of the distinction between a SYNDROME and a DISEASE. Is it that a disease has a known ENVIRONMENTAL VECTOR while a SYNDROME is apparently solely causes by genes?

http://en.wikipedia.org/wiki/Introduction_to_genetics

HOW GENES WORK

STUDIES OF TWINS

Please see page 275 for explanations of concordance rate and disconcordance rate.

STUDIES USING GROUPS OR NATIONS AS THE UNIT OF AGGREGATION have the problems addressed in a previous chapter. There are MANY FACTORS that may explain difference among the populations of different nations.

As our knowledge grows public health officials are going to have the navigate the hazardous decisions associated with previous efforts now associated with "eugenics." With knowledge comes the responsibility of doing what can be done. But when doing so becomes, "playing God," it is appropriate for society to take pause and consider the implications. Even the genetic manipulation of crop plants is controversial.

A new field has emerged known as genetic epidemiology.

http://en.wikipedia.org/wiki/Genetic_epidemiology

Family research and other methods are part of this new field of endeavor.

Even social networking may be a factor in conditions such as obesity.

Research is being done on the possible origins of schizophrenia, autism, and depression and many other diseases and conditions and diseases.

http://www.youtube.com/watch?v=wgsBxoJ9z3Q