Design Considerations for Genetic Linkage and Association Studies.

Area of Science:

• Genetic Epidemiology
• Statistical Genetics

Background:

• Designing genetic studies requires careful consideration of various factors to ensure statistical power and validity.
• Common complex diseases often necessitate specific study designs, such as the affected sibling pair design for linkage analysis.

Purpose of the Study:

• To outline key considerations for designing linkage and association studies in genetic epidemiology.
• To provide guidance on power and sample size calculations, marker selection, and potential sources of error.

Main Methods:

• Discusses parametric methods and autozygosity mapping for rare Mendelian diseases.
• Focuses on the affected sibling pair design for complex diseases, including power and sample size calculations.
• Examines case-control designs for association studies, including one-stage and multistage approaches, and considerations for genome-wide association studies (GWAS).

Main Results:

• Provides power and sample size calculations as a function of genetic effect strength.
• Highlights the impact of disease heterogeneity, errors, marker type/density on statistical power.
• Warns against underpowered replication studies and discusses risks of spurious associations from population stratification and bias.

Conclusions:

• Effective study design is crucial for reliable genetic epidemiology research.
• Careful planning regarding sample size, marker selection, and potential biases is essential for valid results.
• Awareness of common pitfalls can prevent spurious findings in linkage and association studies.