['Increased dopaminergic activity may play a primary role in psychotic depression. Dopamine beta-hydroxylase (DbetaH) catalyses the key step in biosynthesis of the neurotransmitter noradrenaline from dopamine, and low DbetaH activity is a possible risk factor for developing psychotic depression. An exon 2 polymorphism (DBH*444 g/a) of the DbetaH gene (DBH) is significantly associated with both serum and cerebrospinal fluid levels of DbetaH.', 'We determined the genotype of the DBH*444g/a polymorphism in a cohort of 164 patients with major depression and examined the association of this polymorphism with paranoid ideation, interpersonal sensitivity, and psychoticism on the Hopkins Symptom Checklist.', 'Patients who possessed the A allele were significantly more likely to have higher scores for interpersonal sensitivity and paranoia than patients without the A allele (p =.004 and p =.048, respectively), suggesting that this allele may predispose patients to paranoia in major depression. In addition, we found an association between prolactin levels in men and DBH*444 g/a genotype such that homozygous G individuals displayed significantly higher levels than homozygous A or heterozygote individuals.'] Is a polymorphism in the dopamine beta-hydroxylase gene associated with `` paranoid ideation '' in patients with major depression?