BDNF methylation and mRNA expression in brain and blood of completed suicides in Slovenia

Table 1 Comparisons of the methylation levels across the BDNF regions in the control subjects and suicide victims

Tissue	Study group	BDNF region (% methylated)
		I1	I2	II	IV	VI
Brain-BA9	C	4.55 ± 0.45	4.43 ± 0.39	8.48 ± 0.91	3.81 ± 0.32	3.37 ± 0.30
	SV	4.15 ± 0.56	4.28 ± 0.32	8.78 ± 1.09	4.03 ± 0.46	3.05 ± 0.23
	P value	0.260	0.557	0.667	0.418	0.090
Brain-Hippocampus	C	4.76 ± 0.48	4.16 ± 0.44	10.19 ± 0.51	3.74 ± 0.46	3.46 ± 0.34
	SV	4.40 ± 0.39	4.60 ± 0.43	10.30 ± 1.10	3.66 ± 0.37	3.52 ± 0.31
	P value	0.222	0.147	0.851	0.772	0.774
Blood	C	7.81 ± 1.03	6.83 ± 0.64	15.95 ± 1.36	5.71 ± 0.39	5.38 ± 0.95
	SV	7.00 ± 0.80	5.67 ± 0.57	14.26 ± 1.2	5.54 ± 0.38	4.80 ± 0.46
	P value	0.198	0.007a	0.067	0.521	0.245

^aPcorr < 0.05 (Benjamini–Hochberg method). The studied regions are labelled with Roman numerals (I, II, IV, and VI) according to the vicinity of the exons 1, 2, 4, or 6. The region preceding the first exon (I) is divided into two parts, I1 and I2 due to technical reason of maximum amplicon length recommendation for 454 GS Junior sequencing system (400 bp/region, including 454 GS Junior sequencing primers). Data are means ± 95% confidence interval. C: Controls; SV: Suicide victims. BA9: Brodmann area 9.

Table 2 BDNF alternative transcript expression in brain Brodmann area 9 and hippocampus in controls and suicide victims

Tissue	BDNF transcript	Total	Subjects				P value	95%CI
		Analyzed	Controls		Suicide victims
		n (%)	n (%)	Relative expression	n (%)	Relative expression
BA9	NM_170731.4	30	15	0.050 ± 0.013	15	0.077 ± 0.024	0.042a	0.001–0.054
	NM_170732.4	35	19	0.139 ± 0.026	16	0.154 ± 0.036	0.451	-0.026–0.058
	NM_170733.3	38	20	0.162 ± 0.027	18	0.188 ± 0.044	0.270	-0.022–0.075
	NM_170735	30	15	0.103 ± 0.019	15	0.095 ± 0.019	0.553	-0.033–0.018
Hippocampus	NM_170731.4	36	16	0.342 ± 0.117	20	0.312 ± 0.069	0.630	-0.154–0.094
	NM_170732.4	35	17	0.420 ± 0.120	18	0.369 ± 0.067	0.428	-0.181–0.079
	NM_170733.3	37	18	0.466 ± 0.111	19	0.475 ± 0.061	0.878	-0.111–0.129
	NM_170735	36	18	0.399 ± 0.092	18	0.341 ± 0.073	0.308	-0.171–0.056

^aNominal statistically significant difference (P < 0.05) two-tailed Student’s t test for two independent samples. CI: Confidence interval. BA9: Brodmann area 9.