Associations of BDNF promoter methylation with the morbidity and suicidal ideation in patients with first-episode major depressive disorder

Abstract

Objective To explore the role of brain derived neurotrophic factor(BDNF) promoter methylation for the morbidity of depression patients, and to investigate the relevance between BDNF promoter methylation and the suicidal ideation in patients with first-episode major depressive disorder. Methods The peripheral blood samples from 23 cases of depression patients with suicide ideation, 24 cases of depression patients without suicide ideation, and 27 healthy controls were grouped using simple randomization method, and the methylation status of CpG island of BDNF promoter were subsequently evaluated using bisulphite sequencing. Results The methylation rates(median, quartile interval) of depression patients with suicidal ideation, depression patients without suicidal attempt, and the healthy control were detected as follows, CPG-1: 2.60 (0.28), 2.70 (0.60), 6.40 (1.00); CPG-2: 3.35 (1.15), 3.20 (1.00), 14.50 (2.60); CPG-3: 1.50 (0.40), 1.50 (0.60), 4.60 (0.90); CPG-4: 1.75 (0.90), 1.50 (0.50), 3.90 (0.90); CPG-5: 0.80 (0.58), 0.90 (1.00), 5.70 (2.10); CPG-6: 6.05 (1.03), 6.20 (1.70), 14.50 (1.70); CPG-7: 10.55 (1.68), 10.10 (1.50), 14.70 (1.70); CPG-8: 16.35 (0.90), 16.40(1.00), 4.80 (1.20); CPG-9: 4.20 (4.80), 4.70 (1.30), 28.50 (19.30); CPG-10: 10.25 (1.08), 10.30 (1.20), 4.30 (0.90); CPG-11: 62.80 (4.05), 62.30 (4.00), 37.20 (2.60); CPG-12: 5.60 (1.05), 5.60 (1.30), 12.30 (1.80); CPG-13: 4.15 (1.10), 4.10 (1.10), 59.70 (4.90); CPG-14: 5.45 (0.78), 5.70 (0.90), 6.30 (0.60); CPG-15: 3.70 (0.70), 3.90 (1.00), 62.40 (6.50); CPG-16: 8.05 (1.75), 8.10 (1.60), 74.30 (50.90); CPG-17: 3.20 (0.78), 3.20 (0.80), 32.40 (13.20); CPG-18: 1.90 (0.48), 1.80 (0.40), 2.30 (0.30); CPG-19: 35.00 (6.27), 35.20 (3.00), 64.20 (44.70). There was an obvious difference in methylation rate among three groups, which was statistically significant (P<0.01). However, no statistical significance for the methylation rates was observed between the depression patients with suicidal ideation and without suicidal ideation. Interestingly, statistical significance for the methylation rates were observed when compared the depression patients with suicidal ideation with healthy control (P<0.05), and the depression patients without suicidal ideation with healthy control (P<0.05). Conclusion The results show that the association is observed between BDNF promoter methylation and the morbidity of depressive disorder, but not between BDNF promoter methylation and the suicidal ideation of depression patients. Key words: Brain derived neurotrophic factor; Methylation; Depression; Suicide