Concordance analysis of microarray studies identifies representative gene expression changes in Parkinson’s disease: a comparison of 33 human and animal studies

Table 1 Average concordance of differential gene expression signatures in microarray studies

Subset	Number of studies	Average concordance of expression signatures
PD studies plus Alzheimer’s disease and glioblastoma studies	42	0.04
All PD studies	33	0.05
Species
Human (inc. human cell lines)	19	0.08
Human patients	15	0.15*
Mouse models	9	0.03
Rat models	4	−0.04
Disease model
All neurotoxic models	12	0.03
MPTP	6	0.09
MPTP, mice only	5	0.10
6-OHDA	4	−0.03
Genetic models	3	0.12
Tissue
Basal ganglia (SN (excluding isolated dopaminergic neurons) and striatum)	18	0.10*
SN: tissue	8	0.30*
SN: isolated dopaminergic neurons	4	0.03
Striatum	9	0.07
Platform
Affymetrix	27	0.06
U133 and U133 Plus arrays (human studies only)	12	0.10

Asterisks indicate subgroups where concordance is within the top 5% of concordance values over randomly sampled subgroups of PD studies. The threshold for significance varies with the number of studies in the subset (see Methods, Additional file 12). Concordance estimates for smaller subgroups should be regarded as less reliable, as the average concordance is more sensitive to variation in individual studies

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