Around 25% of the world is affected by a psychiatric disorder that can alter their behaviour, social relations and intellectual ability.

A study recently published in Cell has published the largest genetic map of psychiatric disorders, where 109 genetic variants associated with eight disorders: autism, anorexia nervosa, ADHD, schizophrenia, bipolar disorder, depression, obsessive-compulsive disorder (OCD) and Tourette Syndrome.

The study was based on a total of 230,000 patients worldwide and 500,000 controls and was promoted by the Psychiatric Genomics Consortium. As well as listing the genetic predisposition to the disorders, the study determines the genes that the disorders share and completes the genetic map of psychiatric disorders.  The results of the study show a gene that is related to the development of the nervous system, DCC, is a risk factor for all eight disorders and a splicing gene RBFOX1 is involved in seven of the eight disorders.

The study also defines three groups for the disorders: those which are compulsive behaviours (e.g. anorexia nervosa or OCD), those that are mood or psychotic disorders (e.g. depression, bipolar disorder, and schizophrenia), or early-onset neurodevelopmental disorders (e.g. autism, Tourette syndrome or ADHD).

Bru Cormand, Head of the Neurogenetics Research Group at the University of Barcelona states that the disorders that are listed in the same group tend to share more genetic risk factors and that the groups that are built based on genetic criteria match with the clinical output.  He also states, however, that the study does not emphasise the genes shared by members of a group, but on the genes shared by the highest number of disorders. The factors would somehow give way to a “sensitive” brain that is more likely to suffer from a psychiatric disorder, and there are also environmental factors.

As well as genomics, the study focuses on the analysis of functional aspects of the genetic risk variants.

As some of the disorders are co-morbid, a better understanding of the genetics behind patient predisposition could help understanding of what else they may be susceptible to.