ABSTRACT
Differentially expressed clones from subtracted cDNA libraries of a pair of monozygotic twins discordant for schizophrenia have been reported in the literature. The clones were expressed in lymphocytes from the healthy twin, but not from the schizophrenic twin. In the current study, we assessed the expression of one of these clones, oksc12b, in 10 normal controls and in 10 patients who met DSM-IV criteria for schizophrenia and had never received neuroleptic medication. We hypothesized that this clone would be differentially expressed in normal controls and in the schizophrenic patients, and that its expression could be a peripheral marker of the disease. Lymphocytes were isolated and total RNA was purified, reverse-transcribed, and quantified by two PCR methods. In the first PCR assay, oksc12b expression was measured relative to beta-actin gene expression. The second PCR assay consisted of a competitive procedure using a heterologous DNA internal standard. Neither method confirmed any difference in oksc12b expression between schizophrenic patients and normal controls. Subtypes of schizophrenia or the general heterogeneity of this syndrome may explain the discrepancy found. It is also possible that the differentially expressed clones are present in discordant monozygotic twins, but not in other patients.