Toll-like receptor (TLR) 3 polymorphism, Leu412Phe (TLR3 Leu412Phe, L412F; rs3775291) variant, which results in accelerated disease progression and increased risk of mortality in idiopathic pulmonary fibrosis (IPF), was also found to be significantly associated with the development of a chronic clinical phenotype in pulmonary sarcoidosis [18,19]. This evidence concerns the gene TLR3 and idiopathic pulmonary fibrosis.