CTHRC1 (collagen triple helix repeat containing 1) is a gene whose expression defines pathogenic fibroblasts in SSc and idiopathic pulmonary fibrosis (IPF) fibrotic lung specimens (33) and is a marker along with LRRC15 for myofibroblasts across tissues (16). This evidence concerns the gene LRRC15 and idiopathic pulmonary fibrosis.