Epigenetic Changes of Serotonin Transporter in the Patients with Alcohol Dependence: Methylation of an Serotonin Transporter Promoter CpG Island

Abstract

ObjectivePsychiatric disorders such as depression, anxiety and alcohol dependence are associated with serotonin metabolism. We assessed the methylation level of the serotonin transporter (5-HTT) promoter region in control and alcohol dependent patients.MethodsTwenty seven male patients who met the Diagnostic and Statistical Manual of Mental Disorder IV (DSM-IV) criteria for alcohol dependence were compared with fifteen controls. Polymerase chain reaction (PCR) assays of bisulfate-modified DNA were designed to amplify a part of the CpG island in the 5HTT gene. Pyrosequencing was performed and the methylation level at seven CpG island sites was measured.ResultsWe found no differences in the methylation patterns of the serotonin transporter linked promoter region (5-HTTLPR) between alcohol-dependent and control subjects.ConclusionOur negative finding may be because 5-HTT epigenetic variation may not affect the expression for 5-HTT or there may be other methylation site critical for its expression. To find out more conclusive result, repeating the study in more methylation sites with a larger number of samples in a well-controlled setting is needed.