The association study cohort is composed of Costa Rican subjects: i) 3 extended families with SZ and BD (N = 107); ii) unrelated individuals with diagnoses of SZ (n = 390) and BD (n = 368); and iv) unrelated controls (N = 507) with no family history of SZ, BD, suicide or hospitalization for psychiatric reasons, with no self-reports of suicide attempts, psychosis, diagnosis of SZ, BD, or use of medications for depression or psychiatric conditions. A total of 1372 subjects participated, including 422 SZ (44.1% male), 382 BD (42.1% male) and 507 control subjects (56.9% males). All subjects were ascertained in the Costa Rica Central Valley (CRCV) by a psychiatrist, and only subjects whose four grandparents were of Spanish descent were included in this cohort. At the time of blood sampling, for all study participants structured interviews, summaries of hospital records, and family history information was obtained by a trained interviewer. Details about enrolment criteria and clinical definitions have been described elsewhere (Moon et al., 2011). The study was approved by the Ministry of Health of Costa Rica and
