Intriguingly, there seems to be a threshold of FOXP3 protein level to be functional, since Tregs fail to suppress spontaneous autoimmunity in transgenic mice harboring FOXP3 gene with manipulated 3′ untranslated region (UTR) for translating about tenfold decrease in Foxp3 protein (Wan and Flavell, 2007). This evidence concerns the gene FOXP3 and Autoimmunity.