In a study published in Nature Genetics, Cato Romero, Mats Nagel, and Sophie van der Sluis teamed up with colleagues from the Complex Trait Genetics department and the Million Veteran Program to scrutinize the genetic similarity of twelve psychiatric disorders. 

Comorbidity among psychiatric disorders could be due to different disorders sharing the same genetic risk factors. Pinpointing genetic variants and biological processes shared between psychiatric disorders is essential to improve treatment of these debilitating disorders and can potentially even lead to genetically informed therapy (e.g., drug development, drug repurposing) and genetically informed adaptation of our diagnostic system.

In the paper by Romero et al., considerable genetic overlap was detected between psychiatric disorders in the form genetic variants (SNPs), genes, and genomic regions, to overlapping functional annotations; however, the majority of overlap was between pairs of psychiatric disorders. Only genomic regions related to evolutionary conservation were associated to most (9 out of 12) psychiatric disorders, which suggests genetic variation in essential biological processes as a common feature of psychiatric disorders.

Beyond the degree of genetic overlap, Romero et al. showed that variation in statistical power and genetic architecture crucially determines the potential success of future cross-trait genetic research. As more and more genetic data is being collected and shared, it is a matter of time before circumstances for genetic comorbidity research improve to live up to its potential.

Global genetic correlations between the twelve psychiatric disorders.