The identification of new genetic variants underlying psychosis is crucial to improve its molecular diagnosis and to determine the disease etiology, which is necessary to develop new therapeutic targets.

To identify novel rare genetic variants associated to mental disorders, using whole exome sequencing (WES).

Two families with high prevalence of mental disease were genotyped using WES. The first family has 5 members affected, the mother with a bipolar disorder, three sons, two with schizophrenia and one with schizoaffective disorder, and a cousin with major depression and psychotic symptoms. The second family is constituted by 38 members affected by major mental diseases in three generations. Key affected members of each family were genotyped by WES. Shared rare variants, with allelic frequencies below 0.5% in general population, were identified among the affected members of the family. The segregation of those variants was confirmed by Sanger sequencing.

In family 1, thirty-seven genetic variants related to neurodevelopment were identified. Two of those variants in the genes TRIP12 and RNF25 segregated with psychosis. In family 2, seven rare genetic variants contained in genes related to neurodevelopment were identified. A mutation in the gene ARHGAP19 segregated with psychosis.

Three new genes have been found to be associated with psychosis. TRIP12 and RNF25 encode two E3-ubiquitin ligases which modulate the Wnt pathway, mutations in which lead to neurodevelopmental defects. ARHGAP19 encodes a GTPase which regulates the RhoA protein, involved in the regulation of the cytoskeleton.

The authors have not supplied their declaration of competing interest.