IL1RN and idiopathic interstitial pneumonia: A meta-analysis offive studies of IPF patients compared with healthy controls (thenumbers of IPF patients in samples are 88, 61, 54, 22 and 77from different countries) revealed the haploblock VNTR*2 ofthe IL1RN gene (encodes an interleukin-1 receptor antagonist),associated with susceptibility to the development of sporadicIPF (Korthagen et al., 2012).