Development of a Genetic Test Indicating Increased AVP/V1b Signalling in Patients with Acute Depression

A subgroup of patients with acute depression show an impaired regulation of the hypothalamic-pituitary-adrenocortical axis, which can be sensitively diagnosed with the combined dexamethasone (dex)/corticotropin releasing hormone (CRH)-test. This neuropathological alteration is assumed to be a result of hyperactive AVP/V1b signalling. Given the complicated procedure of the dex/CRH-test, this study aimed to develop a genetic variants-based alternative approach to predict the outcome of the dex/CRH-test in acute depression.Using data of a representative cohort of 352 patients with severe depression participating in the dex/CRH-test, a genome-wide interaction analysis was performed starting with an anchor single nucleotide polymorphism located in the upstream transcriptional region of the human V1b-receptor gene to predict the adrenocorticotropic hormone (ACTH) response to this test. A probabilistic neural-network-algorithm was used to develop the optimal prediction model.Overall prediction accuracy for correctly identifying high ACTH responders in the dex/CRH-test was 93.5% (sensitivity 90%; specificity 95%). Analysis of pituitary RNAseq expression data confirmed that the identified genetic interactions of the gene test translate into an interactive network of corresponding transcripts in the pituitary gland, which is the biologically relevant target tissue, with the aggregated strength of the transcript interactions significantly stronger than expected from chance.The findings suggest the suitability of the presented gene test as a proxy for hyperactive AVP/V1b signalling during an acute depressive episode, highlighting its potential as companion test for identifying patients with acute depression whose pathology can be optimally treated by specific drugs targeting the AVP/V1b-signaling cascade.