Association Between The Methylation Status Of TPH2 Gene And The Risk Factors And Suicidal Behaviors In Mental Disorders

Suicide is a serious public health issue, and more than 90% occurs in the mental disorder population; 15% of the depression and 10% of the schizophrenia eventually die of suicide. Suicide is related with genetic factors, patienthood, psychological and social factors, early life trauma, nerve biochemistry and other factors. Neural biochemical metabolic disorders play an important role in it, such as the TPH2 gene expression disorder will directly interfere with the central nervous system 5- the serotonin pathway, and make it appear suicidal tendencies easily. Research shows that DNA methylation involved in the regulation of gene expression. TPH2 gene promoter of mental disorder patients who commit suicide whether occurs methylation or not, to what extent and its relationship between suicidal behavior, no literature has reported yet. To better understand the social risk factors and nerve biochemistry in mental disorder suicide crowd, we studied the suicide-related factors and changes in TPH2 gene DNA methylation patterns from the perspective of epidemiology and epigenetics. So we could be at the molecular epidemiology level to find the relevant factors of suicidal behavior, earlily identify the high-risk populations and have effective suicide intervention.We conducted a case-control study and divided mental disorder patients into suicide group and non-suicide group. We collected their clinical data and peripheral venous blood samples, extracted DNA, detected the methylation status of TPH2 gene promoter with MSP, and analyzed clinical data and tested the results and its association with suicidal behavior.Our study found that the suicidal behavior of mental disorder patients was in a ratio of 14.74%. Suicidal behavior in mental disorder patients was related with sex, marital status, age of onset, type of disease and negative life events. Suicidal behavior in schizophrenia patients was related with the severity of the illness, anxiety and depression, hostility and suspicions. Suicide in depression patients was related with cognitive impairment and the sense of despair. Marital status(married), type of illnesses (schizophrenia and depression)and negative life events were the risk factors for suicide; in addition to the type of diseases, their OR values were 3.119 and 2.393. In mental disorders, the TPH2 gene promoter methylation frequency of suicide group was lower than those of non-suicide group; in schizophrenia suicide patients, the level of methyl reduced. The results suggested that marital status(married), negative life events were the risk factors of suicidal behavior in mental disorder patients.Depression and schizophrenia were too. Lower frequency methylation of TPH2 gene promoter may be a kind of defense mechanism to mental disorder suicide patients.