IL1RN and idiopathic pulmonary fibrosis: For example, an increased risk or severity of IPF is associated with polymorphisms in the TLR3, Toll-interacting protein (TOLLIP), and interleukin-1 receptor antagonist (IL-1RA) genes (Whyte et al., 2000; Korthagen et al., 2012; Noth et al., 2013; O'Dwyer et al., 2013).