Molecular mechanisms underlying bipolar affective disorders, in particular rapid cycling,
are unknown. We analyzed peripheral blood mononuclear cells (PBMC) of one individual
patient with rapid cycling syndrome under widely standardized conditions. RNA was
extracted from PBMC of eight blood samples, obtained on two consecutive days (8.00
am, overnight fast) within one particular phase, including two different consecutive
depressive and manic phases, and submitted to screening by microarray hybridizations,
followed by detailed bioinformatic analysis. Phase-specific regulation of genes was
confirmed by quantitative RT-PCR, and validated in additional blood samples obtained
over one year later. Among the phase-specific differentially expressed genes were
genes involved in the regulation of the innate immune response by different mechanisms,
neurodevelopmentally important genes, genes involved in prostaglandin metabolism and
genes encoding the hemoglobins A and B. This case demonstrates a consistent phase-dependent
alteration in PBMC gene expression in rapid cycling which might partly explain some
of the concomitant clinical features, like allergic diathesis. Whether phase-specific
regulation of neurodevelopmental genes in PBMC reflects parallel regulation of these
genes in the brain remains open.
