Computational Diagnostics Group compdiag MPI for Molecular Genetics

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Dept. Vingron
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NGFN Microarray Data Analysis Resource

Prednisone Response in Leukemic Blasts

Stefanie Scheid

Collaborators: Leonid Karawajew, Peter Rhein  (Robert-Rössle-Klinik | Charité Berlin)

We analysed microarray samples from 18 patients with childhood ALL. Gene expression measurements in leukemic blast cells were taken before treatment (day 0) and eight days after prednisone treatment (day 8). In addition, gene expression in B-cells was measured for some patients. In a first step of significance analysis, we discovered a set of about 500 genes showing high intra-patient changes in expression between day 0 and day 8. In this set of genes we found a particular behaviour: many genes do not only change from day 0 to day 8, but also from day 8 towards B-cells. To extract these genes we applied the Jonckheere-Terpstra-test, which is a non-parametric test against the alternative that the median expression values are sorted in ascending or descending order. The top-ranking genes are shown below.

Predresponse example
Figure: Gene expression values of top-ranking genes, whose expression changes consistently from non-treated blasts (d0) to treated blasts (d8) to B-cells (B). Yellow color corresponds to high expression level, blue color corresponds to low expression level. For enhanced visualization, the expression levels were centered per gene and genes were hierarchically clustered thereafter.

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