Considerations in the examination of normal human tissue biospecimens for microarray studies

Biomedical science has rapidly progressed over the past decade through the accessibility and advancements made in biotechnology. The application of these technologies will result in further insight into the mechanics of oncogenesis and to methods on how to diagnose and treat tumors. Integral to these studies is the procurement of well-preserved and well-annotated clinical samples of both tumor and matched normal tissue. A straightforward approach toward implicating a gene's involvement in neoplasia is a comparative analysis between the cells of normal tissue and their corresponding malignant counterparts. An often overlooked component of the entire process, however, is if ''normal'' cells are available for examination, and if available, their overall quality. Due diligence should always be used whenever clinically derived tissue is analyzed, as a number of variables may contribute to artificially bias any subsequent data. The aim of this review is to summarize what these variables are so that by their recognition, the bias they lead to can be avoided in future studies.