Fluidics miniaturization (similar to that used in inkjet printers), fluorescent detection methods, and the evolution of powerful informatics approaches have led to mass-produced “gene chips.” A single assay on a gene chip platform, costing tens to hundreds of dollars, can highly accurately analyze a DNA sample for the presence or absence of millions of variations in hours.10 Systems commercially available for research and clinical applications can measure single base pair changes, small deletions, or duplications in genomes, as well as whole-scale genome rearrangements (Table 1). Possibly the most evident biomedical research use of gene chips that detect single base pair variations has been the ground-breaking approach for learning about the genomic underpinning of common complex conditions known as genome-wide association studies (GWAS).3 These studies are predicated on inexpensively measuring variations known as single nucleotide polymorphisms (SNPs) at known points across the genome in large numbers of individuals (hundreds to tens of thousands) with and without a particular common condition. These genotypes are then queried for associations between genome variants and disease status. The first major GWAS, published in 2005, revealed
