Several genes – most notably MAD1L1 (mitotic arrest deficient 1 like 1) – were repeatedly implicated across the various conceptualizations of the PTSD phenotype. The variants in MAD1L1 also show QTL associations with DNA methylation and splicing. MAD1L1, widely expressed in all tissues and thought to play a role in cell cycle control, has emerged as being GWS-associated with at least two other major mental disorders, schizophrenia31 and bipolar disorder 38 — both of which were excluded among participants in this study but have strong genetic correlations with PTSD in MVP and other cohorts13. These observations and the recent finding of GWS-association with anxiety52, suggest that MAD1L1 may be a general risk factor for psychopathology, possibly contributing to the p factor thought to underlie many serious mental disorders53.
