Table 3 Summary of studies reporting DNA methylation in bipolar disorder and schizophrenia in the same study

Carrard et al., 2011 [49]

40

58

67

32 (8)

42 (10)

42 (12)

40

57

27

HRM assay ^{b, c, e}

Age ^j, sex ^j, symptoms ^j

5-HTR1A ^g for SZ/BD compared to HC and for SZ compared to BD

Gradirivasf et al., 2011 [50]

24

24

24

-

-

-

-

-

-

Bisulfite sequencing and qMSP ^{b, d, e}

Age ^h, sex ^j, genotype ^h, medication (antipsychotics) ^h, marital status ^j, smoking ^j, alcohol abuse ^j, education ^j

No differential methylation of HTR2A (promoter) ^j for most CpG sites except for 1438A/G, 1420 and 1223 polymorphic sites;

Hypomethylation of T120C site in SZ/BD ^h;

Lower methylation in SZ CC allele carriers with increasing age

Li et al., 2014 [51]

6

3

1

24 (7)

47 (11)

-

67

33

-

Methylated DNA immunoprecipitation ^{a, c, f}

Age ⁱ, sex ⁱ

Hypermethylation of ADRB1 ^g, HTR1A ^g, NPAS1 ^g and hypomethylation of COMT ^h in SZ; HNRNPA1 and 56 other genes differentially methylated in both SZ & BD ⁱ;

11 genes were differentially methylated among SZ & BD ⁱ

Nohesara et al., 2011 [52]

20

20

25

-

-

-

-

-

-

Bisulfite sequencing and qMSP ^{b, d, e}

Age ^g, sex, marital status ^j, genotype ^j

Hypomethylation of MB-COMT (promoter) ^h

Higher methylation in SZ with increasing age