Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic lung disease in adults of unknown etiology with an extremely poor prognosis. Disease development is influenced by environmental factors such as cigarette smoking or aerosol disposure, but also by genetic factors. Up to one in five patients with IPF have a family history of interstitial lung disease (FIP). Several susceptibility genes have been identified in the last years and confirmed the role of telomere maintenance (e.g. TERT, TERC, RTEL1) and host defense (MUC5A) as important for disease etiology. Other pathways implicated in disease development are ER stress (SFTPC) and TGF-beta signaling (TGFB1).