A generalized family-based association test for dichotomous traits

Area of Science:

• Genetics
• Statistical Genetics
• Bioinformatics

Background:

• Genotyping technology advances enable large-scale association studies for disease-gene mapping.
• Robust family-based association methods are essential for effective gene discovery.
• Existing methods may not fully utilize available family data or handle complex pedigrees efficiently.

Purpose of the Study:

• To introduce the generalized disequilibrium test (GDT), a novel family-based association method.
• To demonstrate the GDT's superior power and robustness compared to existing methods.
• To improve disease-gene mapping accuracy using comprehensive family genetic data.

Main Methods:

• The GDT utilizes genotype differences across all discordant relative pairs within families.
• It incorporates information from extended pedigrees beyond first-degree relatives.
• The method integrates covariates and family size-based weights, employing a robust statistic independent of large sample theory.

Main Results:

• Computer simulations show the GDT consistently outperforms other tests for common and rare diseases.
• Power improvements exceeding 13% were observed in 6 out of 8 extended pedigree scenarios.
• The GDT identified stronger associations, including a genome-wide significant finding for Type 1 Diabetes at gene UBASH3A (p = 4.3 x 10(-6)).

Conclusions:

• The GDT is a powerful and robust family-based association method for disease-gene mapping.
• It offers substantial power gains by efficiently utilizing extended pedigree information.
• The GDT enhances the identification of genetic associations, proving effective in large-scale genome-wide studies.