espanolAntecedentes: la concurrencia de trastornos por uso de sustancias (TUS) es alta en personas con enfermedades psiquiatricas; Mas importante aun, las personas con ambos trastornos (diagnostico dual) tienen sintomas mas graves. Se han propuesto trastornos psiquiatricos para compartir una susceptibilidad genetica con los TUS. Para explorar esta susceptibilidad genetica compartida, analizamos si alguna de las puntuaciones de riesgo poligenico (PRS) para los trastornos psiquiatricos podria estar asociada al diagnostico dual en pacientes con esquizofrenia (SCZ) o trastorno bipolar (BD). Metodos: Se incluyeron 192 individuos de ascendencia mexicana: 72 con SCZ, 53 con BD y 67 controles no relacionados sin trastornos psiquiatricos. Derivamos calculos de PRS para trastornos del espectro autista, trastorno de deficit de atencion / hiperactivo, BD, depresion mayor y SCZ utilizando estadisticas resumidas de asociacion de genoma previamente publicadas. Resultados: Encontramos que el diagnostico dual tenia una susceptibilidad genetica compartida con el trastorno depresivo mayor (MDD) y SCZ; Ademas, en individuos con BD, PRS podria predecir el diagnostico dual para MDD. Conclusiones: Nuestros resultados refuerzan la nocion de que las personas con diagnostico dual tienen una mayor susceptibilidad genetica a desarrollar ambos trastornos. Sin embargo, se requieren analisis de muestras de mayor tamano para aclarar aun mas como predecir riesgos a traves de PRS dentro de diferentes poblaciones. EnglishBackground: Concurrence of substance use disorders (SUDs) is high in individuals with psychiatric illnesses; more importantly, individuals with both disorders (dual diagnosis) have more severe symptoms. Psychiatric disorders have been proposed to share a genetic susceptibility with SUDs. To explore this shared genetic susceptibility, we analyzed whether any of the polygenic risk scores (PRSs) for psychiatric disorders could be associated to dual diagnosis in patients with schizophrenia (SCZ) or bipolar disorder (BD). Methods: We included 192 individuals of Mexican ancestry: 72 with SCZ, 53 with BD, and 67 unrelated controls without psychiatric disorders. We derived calculations of PRS for autism spectrum disorders, attention-deficit/hyperactive disorder, BD, major depression, and SCZ using summary genome-wide association statistics previously published. Results: We found that dual diagnosis had a shared genetic susceptibility with major depressive disorder (MDD) and SCZ; furthermore, in individuals with BD, dual diagnosis could be predicted by PRS for MDD. Conclusions: Our results reinforce the notion that individuals with dual diagnosis have a higher genetic susceptibility to develop both disorders. However, analyses of larger sample sizes are required to further clarify how to predict risks through PRS within different populations. (REV INVEST CLIN. 2019;71:321-9)