The protein encoded by the GCSF Receptor gene is the receptor for colony stimulating factor 3, a cytokine that controls the production, differentiation, and function of granulocytes. The encoded protein, which is a member of the family of cytokine receptors, may also function in some cell surface adhesion or recognition processes. Four transcript variants encoding four different isoforms have been found for this gene, of which three are membrane-bound and the one secreted and soluble. Mutations in this gene are a cause of Kostmann syndrome, also known as severe congenital neutropenia.