[Cis- and trans- mutations in genetic diseases].

Whereas a great number of mutations located in the coding regions of genes have been described, genetic defects involving regulatory elements (cis-) or diffusible effectors controlling gene expression (trans-) are poorly known. Moreover, it appears that the structural defects of transcribed regions of genes have already delivered their "conceptual" message, whereas few studies of the consequences of one single gene defect on the expression of other genes and on in vivo functions are available. In the present communication, we wish to address the following issue: can we take advantage of Nature's experiments, ie. diseases, to extend our knowledge of the coordinate regulation of gene expression, via an original pathway, ie. the pathophysiological pathway? Can we select a few inborn or acquired metabolic diseases as models which could provide insight into as yet unknown factors involved in trans- regulation of gene expression?