BackgroundTelomerase is an enzyme that catalyzes the addition of nucleotides on the ends of chromosomes. Rare loss of function mutations in the gene that encodes the protein component of telomerase (TERT) have been described in patients with idiopathic pulmonary fibrosis (IPF). Here we examine the telomere lengths and pulmonary fibrosis phenotype seen in multiple kindreds with heterozygous TERT mutations.Methods and FindingsWe have identified 134 individuals with heterozygous TERT mutations from 21 unrelated families. Available medical records, surgical lung biopsies and radiographs were evaluated retrospectively. Genomic DNA isolated from circulating leukocytes has been used to measure telomere lengths with a quantitative PCR assay. We find that telomere lengths of TERT mutation carriers decrease in an age-dependent manner and show progressive shortening with successive generations of mutation inheritance. Family members without TERT mutations have a shorter mean telomere length than normal, demonstrating epigenetic inheritance of shortened telomere lengths in the absence of an inherited TERT mutation. Pulmonary fibrosis is an age-dependent phenotype not seen in mutation carriers less than 40 years of age but found in 60% of men 60 years or older; its development is associated with environmental exposures including cigarette smoking. A radiographic CT pattern of usual interstitial pneumonia (UIP), which is consistent with a diagnosis of IPF, is seen in 74% of cases and a pathologic pattern of UIP is seen in 86% of surgical lung biopsies. Pulmonary fibrosis associated with TERT mutations is progressive and lethal with a mean survival of 3 years after diagnosis. Overall, TERT mutation carriers demonstrate reduced life expectancy, with a mean age of death of 58 and 67 years for males and females, respectively.ConclusionsA subset of pulmonary fibrosis, like dyskeratosis congenita, bone marrow failure, and liver disease, represents a “telomeropathy” caused by germline mutations in telomerase and characterized by short telomere lengths. Family members within kindreds who do not inherit the TERT mutation have shorter telomere lengths than controls, demonstrating epigenetic inheritance of a shortened parental telomere length set-point.

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Heterozygous mutations in four telomere-related genes have been linked to pulmonary fibrosis, but little is known about similarities or differences of affected individuals. 115 patients with mutations in telomerase reverse transcriptase (TERT) (n=75), telomerase RNA component (TERC) (n=7), regulator of telomere elongation helicase 1 (RTEL1) (n=14) and poly(A)-specific ribonuclease (PARN) (n=19) were identified and clinical data were analysed. Approximately one-half (46%) had a multidisciplinary diagnosis of idiopathic pulmonary fibrosis (IPF); others had unclassifiable lung fibrosis (20%), chronic hypersensitivity pneumonitis (12%), pleuroparenchymal fibroelastosis (10%), interstitial pneumonia with autoimmune features (7%), an idiopathic interstitial pneumonia (4%) and connective tissue disease-related interstitial fibrosis (3%). Discordant interstitial lung disease diagnoses were found in affected individuals from 80% of families. Patients with TERC mutations were diagnosed at an earlier age than those with PARN mutations (51±11 years versus 64±8 years; p=0.03) and had a higher incidence of haematological comorbidities. The mean rate of forced vital capacity decline was 300 mL·year−1 and the median time to death or transplant was 2.87 years. There was no significant difference in time to death or transplant for patients across gene mutation groups or for patients with a diagnosis of IPF versus a non-IPF diagnosis. Genetic mutations in telomere related genes lead to a variety of interstitial lung disease (ILD) diagnoses that are universally progressive.

Background The INBUILD trial investigated the efficacy and safety of nintedanib versus placebo in patients with progressive fibrosing interstitial lung diseases (ILDs) other than idiopathic pulmonary fibrosis (IPF). We aimed to establish the effects of nintedanib in subgroups based on ILD diagnosis. Methods The INBUILD trial was a randomised, double-blind, placebo-controlled, parallel group trial done at 153 sites in 15 countries. Participants had an investigator-diagnosed fibrosing ILD other than IPF, with chest imaging features of fibrosis of more than 10% extent on high resolution CT (HRCT), forced vital capacity (FVC) of 45% or more predicted, and diffusing capacity of the lung for carbon monoxide (DLco) of at least 30% and less than 80% predicted. Participants fulfilled protocol-defined criteria for ILD progression in the 24 months before screening, despite management considered appropriate in clinical practice for the individual ILD. Participants were randomly assigned 1:1 by means of a pseudorandom number generator to receive nintedanib 150 mg twice daily or placebo for at least 52 weeks. Participants, investigators, and other personnel involved in the trial and analysis were masked to treatment assignment until after database lock. In this subgroup analysis, we assessed the rate of decline in FVC (mL/year) over 52 weeks in patients who received at least one dose of nintedanib or placebo in five prespecified subgroups based on the ILD diagnoses documented by the investigators: hypersensitivity pneumonitis, autoimmune ILDs, idiopathic non-specific interstitial pneumonia, unclassifiable idiopathic interstitial pneumonia, and other ILDs. The trial has been completed and is registered with ClinicalTrials.gov, number NCT02999178.

Background Short telomere lengths are found in a subset of idiopathic pulmonary fibrosis (IPF) patients, but their clinical significance is unknown. The aim of this study was to investigate whether patients with various blood leukocyte telomere lengths had different overall survival. Methods Telomere lengths were measured in 370 genomic DNA samples isolated from peripheral blood collected from patients with interstitial lung disease (149 with IPF) at the time of their initial evaluation. Associations of telomere length with transplant-free survival were determined. Findings were validated in two independent IPF cohorts. Findings Patients with IPF had shorter telomere lengths than controls, but similar telomere lengths when compared to patients with other interstitial lung disease diagnoses after adjusting for age, male sex and ethnicity. Telomere length was independently associated with transplant-free survival time for patients with IPF (HR 0·22 [0·08–0·63], P-value = 0·0048), but not for patients with interstitial lung disease diagnoses other than IPF (HR 0·73 [0·16–3·41], P-value = 0·69). The association between telomere length and IPF survival was independent of age, male sex, forced vital capacity or diffusing capacity of carbon monoxide (and was replicated in two independent IPF cohorts (HR 0·11 [0·03–0·39], P-value 0·00066; HR 0·25 [0·07–0·87], P-value = 0·029). Addition of telomere length to clinical prediction models improved the integrative discrimination index, especially for IPF cohorts with milder disease. Interpretation These findings suggest that shorter leukocyte telomere lengths are associated with worse survival in IPF. Additional studies will be needed to determine clinically relevant thresholds for telomere length and how this biomarker may influence future risk stratification of IPF patients. Furthermore, this study offers mechanistic insight as disease progression in certain IPF patients may be related to aberrant signaling from short telomeres. Funding US National Heart, Lung, and Blood Institute; the National Center for Advancing Translational Science, the Harroun Family Foundation and the Nina Ireland Lung Disease Program.