Genetic association analysis: lessons from the study of Alzheimers disease.

Association studies are an increasingly popular way to test single nucleotide polymorphisms and other gene sequence variations for their involvement in complex disease. Alzheimers Disease has provided an ideal test-bed for the field, and it continues to be a particularly instructive disease model. Research findings demonstrate the difficulties faced by the field, and help to suggest effective ways to improve the phenotype and the genotype aspects of research practice in the field. Technical obstacles remain to be solved, but they have been well-defined by early experiences with SNP and haplotype analyses, the elucidation of other confounding forms of genome variation, and the emergence of a global haplotype map. With the adoption of more sophisticated research strategies and continued advancement in high-throughput genotyping technologies, many genetic contributors to common disease will probably be identified, leading to better predictive and diagnostic medicine in the relatively near future.