Hss4303b – Intro to Epidemiology

Hss4303b – Intro to Epidemiology

March 18, 2010 – Molecular & Genetic Epidemiology

But first….

• Don’t forget to choose your marking scheme– Option #1: midterm=25, final = 40– Option #2: midterm=20, final=45

• Deadline is March 29, midnight• Link is on the website

Last time….

• I asked a question

?

What’s a “Natural Experiment”?

• Eg, compare two communities with similar demographics, but one has a smoking ban and the other doesn’t; follow prospectively to see the rate of heart disease that arises– Is this not a cohort study?

Molecular Epidemiology

• Term first used in 1973 by Kilbourne– Referred to the emergence of the “biomarker” as a

tool for strategizing the addressing of disease• What’s a biomarker?• A substance used as an indicator of a biological

state– Can be something introduced into an organism to be

tracked – Can be something innate to the organism whose state

changes in response to disease status

Molecular Epidemiology

• University of Pittsburgh (J. Dorman):– “a science that focuses on the contribution of

potential genetic and environmental risk factors, identified at the molecular level, to the etiology, distribution and prevention of disease within families and across populations“

• The marriage of traditional epidemiology and molecular biology

• Closely associated with genetic epidemiology

See the key difference?

Many of the following slides

• Taken from:

• By Dr Janice Dorman

http://www.pitt.edu/~super1/lecture/lec0131/005.htm

Objectives of Molecular Epidemiology

1. Descriptive and analytical studies to evaluate host/environmental interactions in disease

2. The development of prevention strategies for the control of bacterial, parasitic and viral disorders through molecular diagnosis

3. The prevention of non-communicable diseases and genetic disorders by assessing risk and identifying susceptible individuals through genetic screening

-Univ of Pittsburgh

However• Few nations currently have resources (labs, etc)

and expertise to conduct molecular epidemiology research

• Establishment of “International Molecular Epidemiology Task Force” (IMETF)1. To facilitate the development and implementation

of programs in molecular epidemiology in all regions of the world

2. To promote advanced biotechnology transfer for scientific research and its integration into epidemiology, medicine and public health for disease prevention

http://www.pitt.edu/~kkr/international.html

http://www.ornl.gov/sci/techresources/Human_Genome/home.shtml

Human Genome ProjectCompleted in 2003. Project goals were to :

•identify all the approximately 20,000-25,000 genes in human DNA, •determine the sequences of the 3 billion chemical base pairs that make up human DNA, •store this information in databases, •improve tools for data analysis, •transfer related technologies to the private sector, and •address the ethical, legal, and social issues (ELSI) that may arise from the project.

Tell me about Type 1 Diabetes?

Type 1 Diabetes

• Although type 1 diabetes is relatively rare, incidence rates vary dramatically across countries.

• The highest rates are in Finland and Sardinia (greater than 20/100,000 per year) and the lowest are in Asia (less than 3/100,000 per year).

• The incidence of type 1 diabetes in the US and Canada is moderate (15-20/100,000 per year)

What Just Happened?• by linking descriptive and analytical molecular

epidemiology studies, we can: – 1) estimate individuals’ relative risk of disease (i.e.,

magnitude of the increase in risk associated with the presence of a specific molecular marker), and also

– 2) determine their absolute risk of disease (i.e., probability of developing the disease) if the molecular markers under evaluation are present.

• Information regarding absolute risk of disease is essential for the development of medical and public health strategies for disease prevention.