Novel design and controls for focused DNA microarrays: applications in quality assurance/control and normalization for the Health Canada ToxArray.

Background: Microarray normalizations typically apply methods that assume absence of global transcript shifts, or absence of changes in internal control features such as housekeeping genes. These normalization approaches are not appropriate for focused arrays with small sets of genes where a large portion may be expected to change. Furthermore, many microarrays lack control features that can be used for quality assurance (QA).