Related Experiment Videos
Tests and estimates of allelic association in complex inheritance
1Human Genetics, University of Southampton, Level G, Princess Anne Hospital, Coxford Road, Southampton SO16 5YA, United Kingdom. nem@soton.ac.uk
Summary
Family-based genetic studies, like the transmission disequilibrium test (TDT), address concerns about population stratification in disease gene mapping. While TDT is less efficient than case-control methods, it offers robustness against population structure.
Area of Science:
- Genetics
- Population Genetics
- Statistical Genetics
Background:
- Family-based association studies were developed to overcome limitations of population-based methods, such as stratification, migration, and admixture, in disease gene mapping.
- The transmission disequilibrium test (TDT) is a primary family-based procedure designed to detect allelic association.
- Key considerations in study design include gene action, efficiency, diagnostic reliability, linkage, imprinting, and sibship composition.
Purpose of the Study:
- To evaluate the transmission disequilibrium test (TDT) as a family-based method for mapping disease genes.
- To compare the efficiency of TDT with traditional case-control designs.
- To assess factors influencing TDT efficiency and its applicability in different study designs.
Main Methods:
- The study focuses on the transmission disequilibrium test (TDT) using family-based samples (parent-offspring pairs and trios).
- Efficiency is compared against case-control designs with unrelated normal and hypernormal controls.
- Factors influencing TDT efficiency, such as family structure and inclusion of normal siblings, are analyzed.
Main Results:
- The TDT demonstrates lower efficiency compared to case-control designs with unrelated controls (e.g., 1/2 for parent-offspring, 2/3 for trios, 1/6 against hypernormal controls).
- Efficiency is generally lower against hypernormal controls than random controls, but can be increased in multiplex families and with normal sibs.
- Family-based designs are justified for mapping disease genes primarily when population stratification is a significant concern.
Conclusions:
- The transmission disequilibrium test (TDT) provides a robust method for disease gene mapping by mitigating population stratification.
- Despite lower efficiency compared to case-control studies, TDT's strengths lie in its ability to handle population structure.
- The choice between family-based and population-based designs depends on specific research questions, population characteristics, and the need to control for confounding factors like stratification.