Table 2.

Overview of the genes tested for a hypothesized association with OCD and the number of probes included 100,000 bp up and down stream of the genetic region – *413 probes were overlapping between GABBR1 and MOG (GABBR1/MOG).

Systems	Gene	Probes (count)	Methylated variable positions (limma) Case vs. ctrl
			OLD (case: N = 21, control: N = 11)	NEW (case: N = 21, control: N = 12)
Glutamatergic system	SLC1A1	28	NS	NS
	SLC25A12	47	NS	NS
	GABBR1	519*	NS	NS
			^cg10234998* (GABBR1, TSS1500), p-val: 0.00023/FDR p 0.18, Fold-change (case/ctrl): 1.14
			^cg17099072* (GABBR1, TSS1500) p-val: 0.00026/FDR p 0.18 Fold-change (case/ctrl): 1.12
	GAD1	87	NS	NS
	DLGAP1	103	NS	NS
	MOG	571*	NS	NS
			^cg10234998* (GABBR1, TSS1500), p-val: 0.00023/FDR p 0.18, Fold-change (case/ctrl): 1.14	^cg16650906 (LOC285830, body) p-val: 0.00017/FDR p 0.12, Fold-change (case/ctrl): 0.976
			^cg17099072* (GABBR1, TSS1500) p-val: 0.00026/FDR p 0.18
			Fold-change (case/ctrl): 1.12
Neurotrophic factors	BDNF	86	NS	NS
				^cg14080521 (BDNF-AS, IGR) p-val: 0.00031/FDR p 0.14, Fold-change (case/ctrl): 0.98
	OLIG2	82	NS	NS
	NTRK3	51	NS	NS
	NTRK2	19	NS	NS
Sex hormone	ESR1	73	NS	NS
				^cg10939667 (ESR1, Body) p-val: 0.00016/FDR p 0.12, Fold-change (case/ctrl): 0.98
Serotonergic system	SLC6A4 (SERT)	63	NS	NS
	TPH2	42	NS	NS
Dopaminergic system	COMT	128	NS	NS

NS, not-significant describes that a FDR corrected p-value of <0.05 was not achieved for any genetic region. However, we have mentioned (bold writing) the top three probes that had p-values <0.2 for each methylation variable position analysis (OLD and NEW) (see the full list of p-values as in Supplementary Material). ^The top three probes with p-values <0.2 are written in bold writing, and location abbreviation of the probe position relative to the gene are: TSS1500, 1500 bp upstream from transcription start site; body, in gene body; IGR, intergenic region.