Human MIP synthase splice variants in bipolar disorder

Alternative splicing allows the production of multiple gene products with different functions from a given sequence, affecting cellular function control. Tissue-specific splicing is most prevalent in the brain. We therefore investigate whether splice variants contribute to complex psychiatric disorders. A database search suggested that the myo-inositol-1-phosphate (MIP) synthase gene, possibly involved in pathophysiology of bipolar disorder, has splice variants.

Human RNA was purified from lymphocytes and postmortem brain. MIP synthase alternative splice variants were amplified using reverse transcription-polymerase chain reaction.

The bioinformatics finding was confirmed in both tissues. No difference in lymphocyte MIP synthase mRNA splice-variant levels was found between bipolar patients and controls. However, patients with family history of a major psychiatric disorder had significantly higher levels of the variant lacking exons 3 and 4 versus patients with no family history and controls.

As alternative splicing may be a mechanism by which the approximately 30,000 genes are amplified in mammalian brain, further studies with other candidate genes for psychiatric disorders are needed.