question about lee filter holder

i've been wondering if it is possible to use a LEE filter holder with an UV filter already in place?

Can you expand more on that? the Lee holders come set up for 1 only or -3 gel filters and you can get set ups for larger (105mm) circulars to sit in front of the gels.

Perhaps your question is can I stack a Lee gel filter holder on top of a circular screw on UV filter? The answer involves what is your lens & camera, what filter thread is the UV filter, how sensitive is your lens and filter to vignetting at the desired (zoom) focal length. Vignetting will be the most obvious potential problem.
Why not take off the UV, is it for protection only? Many would argue it may be doing you more harm to the image than good to your lens. In any case if you add more layers of glass in front of your lens it certainly may cause more harm to your images and won't add anything.
Mike K

You can screw the adapter into a UV filter, unless it is the slim and I am not sure about that. However, it is not recommended and really there is no good reason to do so.

I never use UV filters when shooting landscapes. It should be removed when using the filter holder.

+1 - take the UV filter off

I don't know you would do this either.
There's only one single thread at the end of the lens so you have to make to make a choice - either the adaptor for a filter system or a screw in protector/polarizer/et​c.