Identification of a set of endogenous reference genes for miRNA expression studies in Parkinson’s disease blood samples

Table 4 Changes in the results of the analyses depending on the choice of the reference genes

Reference gene	miR-29a-3p median of difference (IQR)	P value miR-29a-3p	miR-30b-5p median of difference (IQR)	P value miR-30b-5p
Z30	0.76 (-0.23; 2.22)	0.0048	1.75 (0.17; 3.62)	0.0007
RNU24	0.39 (-0.08; 1.34)	0.0151	0.96 (-0.52; 3.39)	0.0075
RNU6B	0.98 (-0.17; 2.12)	0.0007	2.66 (0.2; 4.05)	0.0001
miR-103a-3p	-0.58 (-1.33; -0.05)	0.0003	-1.16 (-2.53; 0.23)	0.0005
Z30- miR-103a-3p	-0.02 (-0.65; 0.6)	0.7997	0.01 (-1.14; 1.32)	0.8221
Z30-RNU24*	0.68 (-0.17; 1.74)	0.0032	1.74 (0.05; 4.26)	0.0009
Z30-RNU24- miR-103a-3p	0.18 (-0.48; 0.71)	0.5473	0.22 (-1.1; 1.63)	0.3422
Z30-RNU24-RNU6B- miR-103a-3p	0.38 (-0.31; 1.23)	0.0511	1.05 (-0.31; 2.41)	0.0092
RNU24-RNU6B	0.85 (-0.02; 1.77)	0.0011	2.37 (0.2; 3.47)	0.0004
RNU24- miR-103a-3p	-0.35 (-0.75; 0.15)	0.0645	-0.7 (-1.54; 1.13)	0.2372
RNU24-RNU6B- miR-103a-3p	0.12 (-0.31; 0.91)	0.2097	0.61 (-0.44; 1.95)	0.0494
RNU24-RNU6B-Z30	0.74 (-0.08; 1.86)	0.0013	2.02 (0.1; 3.95)	0.0003
RNU6B- miR-103a-3p	0.04 (-0.41; 0.66)	0.3962	0.51 (-0.4; 1.19)	0.0939
RNU6B-Z30	0.79 (-0.1; 1.98)	0.0011	2.44 (0.17; 3.8)	0.0003
RNU6B-Z30- miR-103a-3p	0.31 (-0.36; 1.01)	0.0733	1.02 (-0.3; 1.99)	0.0119

Different combinations of reference genes lead to different relative expression values of miR-29a-3p and miR-30b-5 in the matched PD pairs, therefore affecting the results of the statistical analyses and leading to discordant evidence. *Best set of reference genes.
The median of difference is calculated as median (expression in cases – expression in controls) within each matched case–control set and it is indicated for a descriptive purpose. IQR = interquartile range. P values were computed using a Wilcoxon matched-pairs signed-ranks test.

ISSN: 1756-0500