Table 1 List of different studies investigated on SNCA-intron1 methylation
From: Hypomethylation of intron1 of α-synuclein gene does not correlate with Parkinson’s disease
Author group | Tissues studied | Number | CpG sites studied in intron1 | Method | Site specific change in methylation as compared to control | Overall SNCA-intron-1 methylation | Correlation with α-SYN |
|---|---|---|---|---|---|---|---|
Jowaed et. al., 2010 [1] | Post-mortem brain samples | SNpc and cortex (n = 6 PD, n = 6 controls), putamen (n = 6 PD, n = 8 control) | 23 CpG sites | Bisulfite/Sanger sequencing | SNpc and Putamen, hypomethylated | Hypomethylated in SNpc, cortex and putamen | Not studied |
Matsumoto et al., 2010 [2] | Post-mortem brain samples | SN (n = 3 PD, n = 1 DLB, n = 3 control) , anterior cingulate cortex (n = 12 PD/DLB, n = 8 control), putamen (n = 7 PD/DLB, n = 4 control) | 13 CpG sites (10th to 22nd as compared to ours) | Bisulfite/Sanger sequencing | Not studied | Hypomethylated only in SN | Not studied |
De Boni et al., 2011 [3] | Post-mortem brain samples | SN (n = 10 LBD, n = 3 control), putamen (n = 15 LBD, control n = 6), cingulate gyrus (n = 15 LBD, n = 6 controls), temporal cortex (n = 15 LBD, n = 6 controls), cerebellum (n = 14 LBD, n = 6 controls) | 19 CpG sites (2nd to 22nd (excepting 13th and 18th as compared to ours) | Bisulfite/next-generation sequencing | Putamen, hypermethylated in limbic and neocortical stages of LBD | Hypermethylated in putamen in case of limbic stage of LBD. Other tissues no significant change | Not studied |
Desplats et al., 2011 [4] | Post-mortem brain samples | Frontal cortex (n = 4 PD, n = 4 DLB, n = 4 control) | Gross methylation of Intron1 region | Methylation sensitive PCR | Not studied | Hypomethylation | Not studied |
Richter et al., 2012 [5] | PBMC | Idiopathic PD (n = 43), monogenic PD (n = 3), controls (n = 37) | 7 CpG sites (16th to 22nd as compared to ours) | Bisulfite/pyrosequencing | Not studied | No significant change | Not studied |
Tan et al., 2014 [6] | PBMC | PD (n = 50), control (n = 49) | 14 CpG sites (10th to 23rd as compared to ours) | Bisulfite/Sanger sequencing | hypomethylated | Hypomethylated | α-SYN expression increased with decreased methylation of intron1 in a small representative group of subjects |
Song et al., 2014 [7] | PBMC | PD (n = 50), control (n = 50) | 13 CpG sites (10th to 22nd as compared to ours) | Bisulfite/pyrosequencing | Non-significant decrease | No significant difference | Not studied |
Ai et al., 2014 [8] | PBMC | PD (n = 100), control (n = 95) | 23 CpG sites | Bisulfite/Sanger sequencing | hypomethylated | Hypomethylation | No difference in α-SYN expression between PD and control |
Pihlstrom et al., 2015 [9] | PBMC and post-mortem brain samples | PBMC (n = 36 PD, n = 36 control), cortex (n = 12 PD, n = 12 control) | Gross methylation of Intron1 region | Methylation sensitive restriction digestion and quantitative PCR | Not studied | Hypomethylation in PBMC but no significant difference in post-mortem brain tissue | No difference in α-SYN expression between PD and control |