Cohort study in Portuguese families finds co-segregation of serious mental illnesses and rare CHD2 variant

This observational cohort study investigated the shared genetic architecture of serious mental illnesses (schizophrenia, bipolar disorder, major depression, and autism) using 173 multiplex families from the Portuguese Island Collection, a founder population. The study did not involve a specific intervention or comparator but analyzed familial patterns and conducted genetic sequencing.

The main results showed that co-segregation of psychotic and mood disorders occurred in 28% of the studied families. Co-segregation of intellectual disability or autism spectrum disorder with schizophrenia and mood disorder phenotypes was demonstrated in 7% of families. In a detailed analysis of one three-generation family using whole-genome sequencing, researchers identified an extremely rare predicted loss-of-function mutation in the CHD2 gene.

No safety or tolerability data were reported as this was a genetic association study. Key limitations include the observational design within a specific founder population, which limits generalizability, and the genetic finding being based on analysis of a single family. The study authors appropriately note that the CHD2 mutation 'suggests' disruption 'may lead to' diverse phenotypes, avoiding claims of proven causation. Practice relevance is not reported, and these findings should be viewed as preliminary genetic associations requiring replication in broader populations.