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Optimal Approach for Analysis of Case-Control Genetic Association Studies (GALA 1)

This study has been completed.
National Heart, Lung, and Blood Institute (NHLBI)
Information provided by (Responsible Party):
University of California, San Francisco Identifier:
First received: October 17, 2005
Last updated: March 8, 2013
Last verified: March 2013
The purpose of this study is to examine the effectiveness of approaches to correct for the effects of population stratification on case-control genetic association studies.

Lung Diseases

Study Type: Observational
Study Design: Observational Model: Family-Based
Time Perspective: Retrospective
Official Title: Case-Control Association Studies and Genetic Confounding

Further study details as provided by University of California, San Francisco:

Biospecimen Retention:   Samples With DNA
Retrospective genetic analysis of DNA; samples collected between 1998-2001

Enrollment: 800
Study Start Date: August 2005
Primary Completion Date: June 2010 (Final data collection date for primary outcome measure)
Detailed Description:


In racially admixed populations, genetic associations may be confounded by population stratification. To control for population stratification, statistical methods that use marker genotype data to infer population structure have been proposed as an alternative to family-based tests of association. However, there are limited empirical data on how these methods perform in real populations. This study will use well characterized populations of Mexican and Puerto Rican asthmatics, their parents, and control subjects recruited from the same sites to examine the effectiveness of approaches to correct for the effects of population stratification on case-control genetic association studies.


This study has three specific aims: 1) To test and compare methods of detecting and correcting for population stratification, the study will genotype a total of 100 ancestral informative markers (AIMs) for 400 asthma cases and an equal number of control subjects. These AIMs will then be used with three statistical methods developed to detect and correct for population stratification. The number and characteristics of markers required to correct false positive associations between AIMs, asthma, and asthma quantitative traits will be evaluated and compared; 2) To compare the power of genomically adjusted case-control studies to the Transmission Disequilibrium Test (TDT). An allele from each of the 100 AIMs will be considered as a risk factor for a simulated "phenotype." The association between phenotypes and each AIM will be tested with the TDT and with a case-control analysis after adjustment for stratification to compare the false negative rates for these study designs. 3) To use the results from aim 1 and 2 to define an optimal approach for analysis and interpretation of case-control association studies in these populations and apply this approach to analyze the association between asthma and a series of candidate genes. The results of these studies should provide important insights into optimal methods to control for population stratification in case-control association studies, thereby facilitating the inclusion of admixed populations in future genetic studies of complex diseases such as asthma.


Ages Eligible for Study:   8 Years to 40 Years   (Child, Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Family-based cross sectional analysis
No eligibility criteria; this study will be using existing blood samples of Mexican and Puerto Rican asthmatics, their parents, and control participants who were recruited prior to the study.
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Please refer to this study by its identifier: NCT00241709

United States, California
University of California, San Francisco
San Francisco, California, United States, 94143
Sponsors and Collaborators
University of California, San Francisco
National Heart, Lung, and Blood Institute (NHLBI)
Principal Investigator: Esteban Gonzalez Burchard, MD University of California School of Medicine, San Francisco
  More Information

Responsible Party: University of California, San Francisco Identifier: NCT00241709     History of Changes
Other Study ID Numbers: 1309
R01HL078885 ( US NIH Grant/Contract Award Number )
Study First Received: October 17, 2005
Last Updated: March 8, 2013

Additional relevant MeSH terms:
Lung Diseases
Respiratory Tract Diseases processed this record on May 25, 2017