The Impact of the Serotonin Transporter Gene Promoter DNA Methylation on Anorexia Nervosa：A Preliminary Longitudinal Study

Abstract

BackgroudThe serotonin system has been reported to be involved in the pathogenesis of anorexia nervosa (AN). The promoter region of serotonin transporter gene (SLC6A4), also called 5-HTTLPR, responsible for serotonin reuptake, has received much attention, especially 5-HTTLPR methylation, which was associated with abnormal eating behaviors. The study was aimed to explore the association between 5-HTTLPR methylation and AN, as well as its predictive effect on therapeutic response.Methods91 AN patients and 87 healthy controls (HCs) were recruited. Only 30 patients completed the 12-week follow-up. 5-HTTLPR methylation levels and clinical symptoms were assessed at baseline for all participants, at the fourth and the twelfth week for follow-up patients. 5-HTTLPR methylation was measured by MassArray methods and clinical symptoms were mainly evaluated by the EDE-Q6.0 scale. ResultsAN patients had higher methylation at CpG 11, CpG 24.25, CpG 31.32 and CpG_mean than healthy controls (P=0.039, 0.042, 0.018, 0.001). Furthermore, it was the binge/purging subtype that revealed significant hypermethylation at CpG4 and CpG_mean (P=0.027, 0.031). However, it failed to discover significant differences between AN-R and AN-BP groups at all units. Besides, CpG 11 methylation level was positively correlated with EDEQ-6.0 total score in patients (r=0.226, P=0.047). The methylation level of CpG11, CpG26.27.28, CpG31.32, CpG33.34.35.36 and CpG_mean decreased after treatment, but not significantly. 5-HTTLPR methylation was not significantly different between the two groups after treatment.ConclusionsOur study provided preliminary evidence that 5-HTTLPR methylation played vital roles in AN pathogenesis. The characteristic of 5-HTTLPR among untreated AN patients was hypermethylation. However, whether it is the biomarker to distinguish the subtypes and therapeutic response of AN needs further investigation.