Abstract
Patients with bipolar disorder have a higher risk of suicide than the general population. This study aimed to explore the correlation between suicide and gene methylation, as screened by genome-wide scanning, in children and adolescents with bipolar disorder. A total of 45 children and adolescents with bipolar disorder were divided into a suicidal ideation group (n = 41), a non-suicidal ideation group (n = 4), a low-risk group (n = 12), and a middle-to-high-risk group (n = 33). A pre-experiment was conducted on the suicidal ideation (n = 6) and non-suicidal ideation groups (n = 4). Blood samples were scanned using an Illumina HD 850K microarray, and methylation levels were analysed. Differential methylation sites among the sample groups were screened from the original data, and genes related to suicide were identified. Methylation of the ABI3BP and DPYSL2 genes was detected by pyrophosphate sequencing and statistically analysed. There was a significant difference in age between the low- and middle-risk groups. The results of GO analysis for the suicidal ideation and non-suicidal ideation groups showed that the differential methylation sites were mainly involved in the interferon-γ-mediated signalling pathway, with the main signalling pathways being the inflammatory bowel disease (IBD) pathway and type 1 diabetes mellitus (T1DM) pathway. There were significant differences in the methylation of ABI3BP, HLA-DQB1, HLA-DRB1, AUTS2, SP3, NINJ2, DPYSL2, and other genes between the suicidal and non-suicidal ideation groups. There was also a statistically significant difference in the gene methylation levels between the two groups. However, there was no significant difference in the degree of methylation of the ABI3BP and DPYSL2 genes between the low- and middle-to-high-risk groups. These results suggest that suicidal ideation is correlated with the methylation levels of differentially methylated genes in children with bipolar disorder. However, the severity of suicide risk in paediatric patients with bipolar disorder may not be correlated with the degree of methylation of the ABI3BP and DPYSL2 genes. Therefore, further validation was required.