Biomedical Engineering Reference
In-Depth Information
15
Molecular Genetics
Xiaozhu Zhang and Andrew J. Sandford
James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary
Research, St. Paul's Hospital, Vancouver, British Columbia, Canada
I.
INTRODUCTION
Cigarette smoking is clearly the major environmental determinant of
COPD. However, interestingly, only a minority of chronic cigarette smokers
develop COPD. This observation demonstrates that other factors are
involved and there are epidemiological data to suggest that some of those
factors are genetic. In this chapter, we will summarize the family and twin
studies that indicate that there is a genetic basis to the development of
airflow limitation. We then review the genes that have been investigated
as potential susceptibility factors for COPD. In common with other
complex genetic diseases, it is likely that several genes will be implicated
in the pathogenesis of this COPD and that there will be an interaction with
environmental factors such as cigarette smoke and air pollution.
II. GENETIC EPIDEMIOLOGY
A.
Family Studies
A condition that is least partially genetically determined would be expected
to cluster in families and this has been shown for COPD (1-3). However,
familial clustering may occur due to common environment conditions rather
than a common genetic susceptibility. Evidence to indicate that genetic fac-
tors are responsible for familial clustering includes the results of studies
where it was shown that the relative risk for COPD was increased in the
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