Expression analysis of SIX3 and SIX6 in human tissues reveals differences in expression and a novel correlation between the expression of SIX3 and the genes encoding isocitrate dehyhrogenase and cadherin 18.

SIX3 and SIX6 are transcription factors expressed during early stages of eye development. Limited expression data for SIX3 and SIX6 are available in the literature but, to date, there are no reports of the relative levels of expression of these genes throughout the human body and in adult tissues in particular. In this paper, we report extensive real-time quantitative PCR analyses of SIX3 and SIX6 expression in many different tissues of the adult human body, including ocular tissues, and a comparison of expression data with that of many other genes to identify similarity in expression. Using this powerful technique, we have detected a novel statistical correlation between the spatial distribution and the quantitative expression of SIX3 and 5 other transcripts including IDH1, the gene encoding the NADP(+)-dependent enzyme isocitrate dehydrogenase, and cadherin 18, type 2 (CDH14). Our data demonstrate that this novel technique can be used to generate hypotheses by comparison of gene expression profiles to identify possible interactions between genes or gene products.