Exposure to early life adversities, as child maltreatment may disturb the whole biological development of a child resulting in different consequences. Among the main underlying mechanisms are epigenetics and DNA methylation. The aim of the study was to access the effects of various factors such as child maltreatment (single or multiple), duration, frequency and age of onset of abuse on DNA methylation. Subjects and methods: 90 children (55 males, 35 females) aged 12-18 years were recruited from adolescent psychiatric outpatient clinics at Al-Hadara University Hospital in Alexandria, Egypt. A Childhood Trauma Questionnaire was used to take the history of child maltreatment. Global DNA methylation was determined by MethylFlash methylated DNA quantification colorimetric kit. Results: Regarding DNA methylation, there was a statistically significant hypomethylation was detected among those who reported exposure to more than one type of child maltreatment than those who reported no exposure or exposure to only one type. Significant difference was also detected between children who were exposed at the age of nine or less and those above 9 years. Moreover, a significant association was found between the duration and frequency of maltreatment in the prediction of DNA methylation. Conclusion: global DNA hypomethylation can be used as a marker to detect exposure to multiple types of child maltreatment. However, it is not about the early child maltreatment alone, but the accumulation of abuse over time and higher frequency of exposure to child maltreatment that causes more global DNA hypomethylation. ARTICLE HISTORY

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Background: For decades, the negative impact of childhood adversity and maltreatment has been limited to the immediate harm and injuries. Recently, several studies connected child maltreatment with further long-term consequences in childhood, adolescents and adulthood among them psychiatric symptoms and disorders. Objectives: We aimed at determining the association between psychiatric consequences and different types of child maltreatment among adolescents between 12-18 years, exploring the role of Oxytocin Receptor Gene Polymorphism (rs2254298) in moderating the relation between different types of child maltreatment and psychiatric consequences and to examine the relation between childhood abuse and global DNA methylation. Methodology: A case-control study was carried out on 90 children aged between 12-18 years divided equally into two groups; cases suffering from psychiatric illness and attending child and adolescent psychiatric outpatient clinics at Al-Hadara University Hospital in Alexandria, Egypt and controls recruited from different outpatient clinics at Alexandria university hospitals. Results: A significant difference was detected between cases and controls regarding four types of child maltreatment; physical abuse, sexual abuse and emotional abuse and neglect. Moreover, a significant positive correlation was detected between these four maltreatment types and depressive symptoms detected by children depression inventory (CDI) and total scale of child behavior checklist (CBCL). However, no significant interaction between OXTR gene SNP rs2254298 and child maltreatment in the prediction of depressive symptoms and total scale of CDI and CBCL, respectively. On the other hand, a significant negative correlation was detected between the means of global DNA methylation and three types of child maltreatment: physical abuse and emotional abuse and neglect.

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