Borderline personality disorder (BPD) is a severe mental health condition influenced by environmental risk factors (for example, interpersonal trauma) and genetic factors. We conducted the largest genome-wide association study (GWAS) meta-analysis of BPD so far, with a discovery sample of 12,339 cases and 1,041,717 controls, and a replication study of 685 cases and 107,750 controls (all participants of European ancestry). We identified 11 independent associated genomic loci and 9 risk genes in gene-based analyses. We observed a single-nucleotide polymorphism heritability of 17.3% and derived polygenic scores (PGS) that predicted 4.6% of the phenotypic variance in BPD on the liability scale. BPD showed the strongest positive genetic correlations with GWAS of post-traumatic stress disorder, depression, attention deficit hyperactivity disorder, antisocial behavior, and measures of suicide and self-harm. Phenome-wide analyses in Vanderbilt University Medical Center Biobank and UK Biobank using BPD-PGS confirmed these associations and also identified associations with other medical conditions, including obstructive pulmonary disease and diabetes. These analyses highlight BPD as a polygenic disorder, with the genetic risk showing substantial overlap with psychiatric and physical health conditions.

BPD is a mental disorder characterized by pervasive instability in emotions, interpersonal relationships and self-image as well as impulsive behavior1,2 (for symptoms, see Supplementary Note). BPD has a prevalence of 0.92–1.90% in Western countries3, with symptom onset typically occurring during adolescence. Women are more frequently diagnosed with BPD than men by a ratio of ~3:1, for which a substantial contribution of diagnostic as well as selection bias has been postulated4,5. Individuals with BPD display high rates of self-harm, suicidal ideation and suicide attempts. BPD shows substantial symptom overlap and comorbidity with other mental disorders5,6, and comorbidity with neurological and somatic health conditions6,7. Although some psychotherapies are effective in treating BPD8, no psychopharmacological treatments have been approved by the US Food and Drug Administration specifically for BPD2,9.

In addition to environmental risk factors such as early interpersonal trauma10,11, genetic factors contribute substantially to disorder risk. Twin and family studies estimate the heritability of BPD to be 46–69%12,13 and demonstrate that the genetic risk for BPD is partially shared with other mental disorders but also with continuous traits; for example, the Big Five personality traits14,15. However, a systematic assessment of shared genetic risk with a broad range of disorders and traits is missing.