"To use microarrays effectively, you have to do both the biology and the math correctly," he says. "SNOMAD and DRAGON supplement other available analysis tools to help researchers make sense of their results. The bottom line, however, is that any result must be confirmed."
SNOMAD, or Standardization and Normalization of Microarray Data, was developed in 2001 by a graduate student in Pevsner's lab, in conjunction with Scott Zeger, Ph.D., chair of biostatistics at the Johns Hopkins Bloomberg School of Public Health. The online computer program processes researchers' microarray data to search for "signal" within the "noise" of normal variation in gene expression levels, says Pevsner.
DRAGON, or Database Referencing of Array Genes Online, ties the results of an individual microarray experiment to other available information. For example, DRAGON cross-references over- and under-expressed genes in a researcher's microarray to five online databases, identifying the genes and pulling together what is already known about their functions and roles in disease. The program can also produce visual displays of the results -- graphs, charts, drawings -- that the researcher can manipulate to see -- really see -- how the results fit together.
"Microarrays are really an exploration, and at the end of the analysis we have to decide if we believe it or not," says Pevsner. "But even with the complexities inherent in the brain, we think microarrays can help improve understanding of neurological disorders."