Most dry yeasts are gluten free, but most liquid yeasts are not. Use Safale US-05 yeast for sure. I know that dry yeast is gluten free as I have used it before and my gluten-intolerant friends have had no problem with it.
Here's a neat-sounding gluten-free pale ale kit they can brew. Basically sorghum syrup as the base:
Hope this helps!
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