Is Dermatillomania Genetic?

Dermatilloma is a skin-picking disorder that not only leads to skin damage, but the severity of the behaviour is directly proportional to the social and emotional distress experienced by the person who engages in the behaviour. Anyone with a skin-picking disorder will testify to the shame and embarrassment the condition causes. People with dermatillomania (official term: excoriation disorder) often suffer in silence, unaware of how common the condition actually is. The explosion of web-based technology has given millions of people suffering from dermatillomania access to information and enabled individuals to seek support anonymously. One of the most common questions asked by people seeking information about skin-picking disorder is, “did I inherit it?”, or, “is it genetic?” Often people asking this question have noticed members of their immediate or extended family having similar habits, which leads them to conclude that they must have inherited the behaviour. This is also a concern for people who do not suffer with skin picking, but have witnessed the debilitating impact it can have on a relative’s life, and are concerned that there may be a possibility that they could inherit the condition. These concerns are not unwarranted as existing family history data seems to suggest that skin-picking disorder is familial.

Heritability of skin-picking disorder

In one study of 60 participants with skin-picking disorders, 28.3% of their first degree family members had the disorder. Skin-picking is also often associated with Obsessive-Compulsive Disorder (OCD). Scientists have identified a genetic marker for OCD, but the onset of OCD is also believed to be triggered by a combination of genetic and external factors. So the question remains, is the familial aspect of skin-picking disorder due to the genetic component of OCD, or are there independent genetic factors associated with skin-picking disorder? A study has shown that individuals with skin-picking disorder, without OCD, are more likely to have a first degree relative with the disorder than individuals with OCD. This suggests that there may be genetic factors associated with skin-picking disorders independent of the genetic contribution to OCD. However, the reality is that research into the condition is still very limited and its causes are unknown. A 2012 twin study examining heritability of skin-picking symptoms, found that skin picking was a relatively common problem, particularly among women and that it tends to run in families mainly due to genetic factors. However, the study also concluded that non-shared environmental factors were also instrumental in the onset of skin-picking symptoms. These findings are backed up by other similar prevalence studies that have found skin-picking disorder to be as common as many other psychiatric disorders, with the most recent suggesting it affects between 2% to 3% of the general population.

The age-old Nature vs Nurture Debate

The reality is that there is still very little hard evidence as to the cause of dermatillomania. There are experts who believe that there definitely is an underlying genetic component resulting in some people having a greater predisposition to becoming skin pickers than others. On the other hand there are many experts who view skin picking as a maladaptive behaviour associated with:

• poor coping skills
• obsessive and compulsive thinking
• poor frustration tolerance

By this definition, skin picking is an impaired response in times of high stress. Studies with mice do seem to suggest that there is a strong genetic component to the cluster of behaviour known as Body-Focussed Repetitive Behaviours (BFRB). In these studies, the removal of a gene led to the mice engaging in excessive grooming similar in presentation to hair–pulling and skin-picking, causing damage to the skin of the mice. This has led researchers to conclude that there is an underlying genetic cause for skin-picking and hair-pulling disorders, and that these disorders are a manifestation of excessive grooming. Genetic factors identified by animal studies include mutation of the Hoxb8 gene, and deficiency of the scaffolding protein SAPAP3. This was consistent with a human genetic association study that variation in the SAPAP3 gene is linked to the onset of grooming disorders.

Future Genetic Research

The good news is that research interest in Body-Focussed Repetitive Behaviours such as skin picking disorder has grown in recent years. The Trichotillomania Learning Centre (TLC) is at the forefront of such research. Trichotillomania, a hair pulling disorder, is clustered with skin picking disorder as a Body-Focused Repetitive Behaviour. The TLC is engaged in an international collaborative research project named the Trichotillomania International Consortium for Research. The ambitious project aims to gain a better understanding of the underlying risk factors for trichotillomania and dermatillomania through genetic research. Genetic information such as blood samples, DNA, and cell lines; as well as clinical data collected through in-depth interviews, will be collected and stored for use in present and future studies. The biological samples and clinical data will be stored in a biobank, which is a type of biorepository, and will become an important resource in hair-pulling and skin-picking disorder research. The biobanks will give multiple researchers in the scientific community worldwide access to data representing larger numbers of people than may be possible if they were to collect this data independently. It also enables multiple uses of the data. The Psychiatric and Neurodevelopmental Genetics Unit (PNGU) in the centre for Human Genetic Research and the Massachusetts General Hospital will be the coordinating site for data collection and management. Additional biobanks have also been established at the University of Cape Town and the University of Stellenbosch in South Africa, with plans to establish additional sites in the near future. It is hoped that this resource will facilitate the much needed research into this condition. However, it is important to recognize that even though research points to genetic influence, the role that neurological, behavioural and environmental factors play in the onset of the condition should not be minimized if effective treatment approaches are to be developed.