Ann Saudi Med 24(3) May-June 2004 www.kfshrc.edu.sa/annals REVIEW ARTICLE

he sequence of the human genome has recently been unraveled.1,2 At the same time, new methods have been introduced that allow for a comprehensive expression analysis of the thousands of genes on the RNA or protein level in a given tissue. As a result, a rapidly increasing number of genes have been identified that may play a role in cancer or other diseases. It is hoped that these findings will eventually lead to clinically useful applications. However, the number of potentially useful candidate genes poses significant problems in the evaluation of their potential utility. Large-scale functional gene analyses and molecular epidemiologic studies are needed for this purpose. Collecting data on molecular epidemiology is often a significant challenge for basic researchers due to limited availability of human tissues with clinical information. Tissue microarray (TMA) technology greatly facilitates large-scale tissue analyses. In this method, up to 1,000 different minute tissue samples can be brought onto one microscope glass slide, and be simultaneously analyzed by all types of in-situ methods. Tissue microarray methodology In tissue microarray (TMA) methodology, minute tissue cylinders (typical diameter: 0.6 mm) are taken from various primary tumor blocks (the “donor ” blocks) and Tissue microarrays for high-throughput molecular patholog