<qa>  What was the most accurate index for the best discriminating genes?cDNA arrays: High-Throughput Quantitative Profiling of Gene Expression: With the advent of high-throughput quantitation of gene expression and cDNA technology, it is now possible to study expression of many genes simultaneously to characterize expression patterns in different breast cancers that may distinguish molecular phenotypes associated with clinical response to a treatment. In a recent report, a molecular classification of leukemia was demonstrated. Bone marrow aspirates taken from 38 patients with acute leukemia were evaluated for expression of 6,817 human genes. The 50 best discriminating genes were used to create a predictive index that was then applied to new samples and was found to accurately assign them as AML or ALL. 