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Is post-traumatic stress disorder in your genes?
Author: Mandi Barnard
Published: 15/11/2016

Can post-traumatic stress disorder (PTSD) be passed down through generations in shared family genes? Could a simple blood test tell if you're genetically predisponsed to this?

These are questions a researcher at Stellenbosch University (SU) is hoping to answer by analysing blood samples of rape victims in KwaZulu-Natal to find epigenetic markers linked to PTSD. Epigenetics is the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself.

Ms Jani Nothling received a scholarship from the South African Medical Research Council (SAMRC) to further her research towards a PhD qualification. She is a PhD candidate and research assistant in the PTSD research team in the Department of Psychiatry of the Faculty of Medicine and Health Sciences.

The team is involved primarily in investigating the molecular aetiology of PTSD. This is a severe, chronic and debilitating psychiatric disorder that can occur after exposure to a traumatic event. This is an event which causes intense fear, helplessness and horror, including - but not limited to - a rape, physical attack, hijacking, motor vehicle accident and combat exposure. 

Nothling applies deoxyribonucleic acid (DNA) methylation profiling to determine differences in the epigenetic profile of victims who develop PTSD compared to those who don't. Differential DNA methylation results from the addition or removal of a methyl group at a section of a gene. DNA methylation or demethylation is responsible for reducing or increasing gene expression, which could result in differences in protein levels.

Differentially methylated genes previously found to be related to PTSD include neurochemicals (e.g. serotonin and dopamine transporter genes), as well as genes associated with brain and neuronal development, the immune system and the hypothalamic-pituitary-adrenal axis (the latter being commonly known as the system responsible for the fight or flight response).

Differentially methylated genes may be responsible for PTSD-specific symptoms such as re-experiencing the trauma, avoidance of reminders related to the trauma and hyper-arousal. "Epigenetics is a relatively new field in psychiatry, especially the investigation of methylation in large number of genes compared to specific genes previously found to be associated with PTSD," said Nothling. "Trauma is an environmental factor which may lead to a change in the epigenetic profile of rape victims."

With this study, she hopes to establish a profile of DNA methylation markers to elucidate the molecular pathogenesis of PTSD in rape victims who develop the disorder.

With the PhD scholarship programme, the SAMRC aims to address the shortage of PhD research degrees graduands in South Africa. The aim, as proposed by the National Health Research Committee in 2011, is to fund the education and training of 1 000 PhD candidates in health sciences over a period of 10 years through a large-scale PhD programme for all health professional catagories with degree-based qualifications.