what is the biggest known functional distance between an enhancer and its target gene (TSS) in cis? since the title seems self explanatory; It would be nice if anybody could provide a reference. I'm looking for a paper that I belive stated around 1.5 Mb but anything above will be cordialy welcomed. thanks a lot

I haven't found 1.5 Mb, but 1 Megabase. This is the case for the shh gene in chicken, where the enhancer element is located 1 Mb upstream. The original article can be found here:

* "A long-range Shh enhancer regulates expression in the developing limb and fin and is associated with preaxial polydactyly."



There are two reviews which are also interesting in this context:

* When needles look like hay: How to find tissue-specific enhancers in model organism genomes
* Remote control of gene expression.