GPR15 and autoimmune polyendocrine syndrome type 1: It may be possible that the consistently downregulated GPR15 expression in APS-1 patients’ Tregs could reflect an opposite pattern than colorectal cancer: Lower expression of GPR15 in peripheral blood Tregs, alternatively lower numbers of GPR15+ Tregs in general, and consequently lower numbers of Tregs in the gastrointestinal compartments potentially unleashing a proinflammatory and autoimmunity-prone microenvironment.