Exon and intron sharing in opposite direction-an undocumented phenomenon in human genome-between Pou5f1 and Tcf19 genes.

BACKGROUND: Overlapping genes share same genomic regions in parallel (sense) or anti-parallel (anti-sense) orientations. These gene pairs seem to occur in all domains of life and are best known from viruses. However, the advantage and biological significance of overlapping genes is still unclear. Expressed sequence tags (ESTs) analysis enabled us to uncover an overlapping gene pair in the human genome. RESULTS: By using in silico analysis of previous experimental documentations, we reveal a new form of overlapping genes in the human genome, in which two genes found on opposite strands (Pou5f1 and Tcf19), share two exons and one intron enclosed, at the same positions, between OCT4B3 and TCF19-D splice variants. CONCLUSIONS: This new form of overlapping gene expands our previous perception of splicing events and may shed more light on the complexity of gene regulation in higher organisms. Additional such genes might be detected by ESTs analysis also of other organisms.