[Inter-individual variability of gene expression detected by biochips].
BACKGROUND
For gene expression profiling in leukemia patients we use array technologies in our laboratory. The assays are based on the comparison of patient and control expression profiles. Expression profile of the control sample should be representative but there is a problem of inter-individual variability in population, because also healthy persons display differences in gene transcription activity. Aim of the study was to characterize expression profiles of controls and to determine variability rate.


RESULTS
The control group comprised 15 "healthy" persons (9 peripheral bloods, 2 bone marrows, 4 cord bloods) from various age categories (0 to 56 years). Expression profiles were detected using Atlas Human Cancer cDNA Expression Arrays (Clontech) with 588 gene probes. Total RNAs were isolated from leukocytes and were reverse transcribed into cDNA. Out of 588 tested genes on average 24% were detected. Inter-individual variability of gene expression profiles of leukocytes from the same tissue did not exceed 25%. Majority of the genes, with significant changes in leukemia patients, was expressed at similar level in the control group, with the exception of bone marrow and cord blood samples that demonstrated higher expression of PCNA, MMP8, MMP9 genes. In bone marrow high PCNA expression could result from active cell proliferation in this tissue. Strong expressions of MMP8 and MMP9 might be associated with the presence of cell precursors because there were not detected in peripheral blood leukocytes. Expression of some genes was tissue specific or followed "ontogenetic" trend.


CONCLUSIONS
The inter-individual expression variability has to be taken into account in expression comparative analyses. In order to minimize the influence of existing variability we use mixed control samples and statistical data processing.
Bruchová
H
H
Ustav hematologie a krevní transfuze, Praha. hana.bruchova@uhkt.cz
Brdicka
R
R
D000328:Adult; D002675:Child, Preschool; D005260:Female; D020869:Gene Expression Profiling; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis