PARN and pulmonary fibrosis: Mutations in telomerase reverse transcriptase (TERT), telomerase RNA component (TERC) 6, poly(A)-specific ribonuclease (PARN), and regulator of telomere length 1 (RTEL1) affect telomere length and stability and are associated with the development of pulmonary fibrosis (Table 1) 38.