['Structural brain anomalies are present at early phases of psychosis. The objective was to examine the impact of Catechol-O-Methyltransferase (COMT) gene variations on brain morphology in first-episode non-affective psychosis. We hypothesized that the low activity-COMT (COMT(L)) allele would be associated with the presence of structural brain changes as assessed by quantitative magnetic resonance imaging (MRI).', 'Fifty-two males and 23 females underwent COMT genotyping and MRI. Patients were categorized into three genetic subgroups: COMT(H/H), COMT(L/H) and COMT(L/L). MRI data were analyzed using BRAINS2. Global and lobar volumes of grey matter (GM) and cerebrospinal fluid (CSF) were compared among the three groups after controlling for total intracranial volume and age of illness onset.', 'COMT(L) carriers showed a significant enlargement of the lateral ventricles (F = 7.13, p = 0.009), right lateral ventricle (F = 5.99, p = 0.017) and left lateral ventricle (F = 6.22, p = 0.015). No other significant differences in any of the brain structures were found among subgroups.'] Is low-activity allele of Catechol-O-Methyltransferase ( COMTL ) associated with increased lateral ventricles in patients with first episode non-affective psychosis?