Searching for candidate genes in the new millennium

Completion of the entire sequence of the human genome is having a profound effect on the strategies biological scientists use to identify disease-associated genes. Laborious positional cloning approaches and traditional functional studies are gradually being transformed by emerging genomic and proteomic databases. Some of the exciting challenges investigators now face are the identification of new genes, determining the function of these genes, defining disease associations, and elucidating correlation between genotype and phenotype. To demonstrate how investigative methods for single-gene disorders are changing, we illustrate one possible approach in the search for the gene underlying the autosomal recessive genodermatosis, acrodermatitis enteropathica.