The article provides a comprehensive review of genetic association studies, which aim to identify common genetic variants that influence susceptibility to common diseases. Over 600 positive associations between common gene variants and diseases have been reported, but most of these associations are not robust, with only a few consistently replicated across multiple studies. The authors discuss the reasons for irreproducibility, including population stratification, linkage disequilibrium, gene-gene and gene-environment interactions, and weak genetic effects. They emphasize the need for caution in interpreting single reports of associations and suggest guidelines for performing and interpreting genetic association studies. The review highlights the importance of meta-analysis and the need for large, well-powered studies to confirm associations. The authors also address ethical considerations and the potential clinical applications of genetic associations, cautioning that widespread clinical use should await more robust evidence.The article provides a comprehensive review of genetic association studies, which aim to identify common genetic variants that influence susceptibility to common diseases. Over 600 positive associations between common gene variants and diseases have been reported, but most of these associations are not robust, with only a few consistently replicated across multiple studies. The authors discuss the reasons for irreproducibility, including population stratification, linkage disequilibrium, gene-gene and gene-environment interactions, and weak genetic effects. They emphasize the need for caution in interpreting single reports of associations and suggest guidelines for performing and interpreting genetic association studies. The review highlights the importance of meta-analysis and the need for large, well-powered studies to confirm associations. The authors also address ethical considerations and the potential clinical applications of genetic associations, cautioning that widespread clinical use should await more robust evidence.