Plasma protein variations in monozygotic twins discordant for schizophrenia

Monozygotic twins discordant for schizophrenia were analyzed by two-dimensional (2-D) gel electrophoresis to identify extrahereditary factors important in the development of schizophrenia. Plasma protein patterns in 2-D gels of monozygotic twins discordant for schizophrenia were found to be significantly less alike than those of normal control monozygotic twins. Several polypeptide spots were found to be elevated in the plasma of the schizophrenic twin. One of these polypeptides, spot 782, was also found to be significantly (p< .001) elevated when schizophrenic patients were compared to unrelated normal control individuals. Spot 782 may be an isoform of haptoglobin. Quantitative variations in some plasma haptoglobin levels were seen between discordant twins, but not between unrelated schizophrenic and normal control individuals.