Determinants of survival after lung transplantation in telomerase-related gene mutation carriers: A retrospective cohort

Syndromic genetic causes of pulmonary fibrosis

PURPOSE OF REVIEW

The identification of extra-pulmonary symptoms plays a crucial role in diagnosing interstitial lung disease (ILD). These symptoms not only indicate autoimmune diseases but also hint at potential genetic disorders, suggesting a potential overlap between genetic and autoimmune origins.

RECENT FINDINGS

Genetic factors contributing to ILD are predominantly associated with telomere (TRG) and surfactant-related genes. While surfactant-related gene mutations typically manifest with pulmonary involvement alone, TRG mutations were initially linked to syndromic forms of pulmonary fibrosis, known as telomeropathies, which may involve hematological and hepatic manifestations with variable penetrance. Recognizing extra-pulmonary signs indicative of telomeropathy should prompt the analysis of TRG mutations, the most common genetic cause of familial pulmonary fibrosis. Additionally, various genetic diseases causing ILD, such as alveolar proteinosis, alveolar hemorrhage, or unclassifiable pulmonary fibrosis, often present as part of syndromes that include hepatic, hematological, or skin disorders.

SUMMARY

This review explores the main genetic conditions identified over the past two decades.

Genomic Profiling for Predictive Treatment Strategies in Fibrotic Interstitial Lung Disease

Idiopathic pulmonary fibrosis (IPF) has traditionally been considered the archetype of progressive fibrotic interstitial lung diseases (f-ILDs), but several other f-ILDs can also manifest a progressive phenotype. Integrating genomic signatures into clinical practice for f-ILD patients may help to identify patients predisposed to a progressive phenotype. In addition to the risk of progressive pulmonary fibrosis, there is a growing body of literature examining how pharmacogenomics influences treatment response, particularly regarding the efficacy and safety profiles of antifibrotic and immunomodulatory agents. In this narrative review, we discuss current studies in IPF and other forms of pulmonary fibrosis, including systemic autoimmune disorders associated ILDs, sarcoidosis and hypersensitivity pneumonitis. We also provide insights into the future direction of research in this complex field.

High risk of lung cancer in surfactant-related gene variant carriers

BACKGROUND

Several rare surfactant-related gene (SRG) variants associated with interstitial lung disease are suspected to be associated with lung cancer, but data are missing. We aimed to study the epidemiology and phenotype of lung cancer in an international cohort of SRG variant carriers.

METHODS

We conducted a cross-sectional study of all adults with SRG variants in the OrphaLung network and compared lung cancer risk with telomere-related gene (TRG) variant carriers.

RESULTS

We identified 99 SRG adult variant carriers (SFTPA1 (n=18), SFTPA2 (n=31), SFTPC (n=24), ABCA3 (n=14) and NKX2-1 (n=12)), including 20 (20.2%) with lung cancer (SFTPA1 (n=7), SFTPA2 (n=8), SFTPC (n=3), NKX2-1 (n=2) and ABCA3 (n=0)). Among SRG variant carriers, the odds of lung cancer was associated with age (OR 1.04, 95% CI 1.01-1.08), smoking (OR 20.7, 95% CI 6.60-76.2) and SFTPA1/SFTPA2 variants (OR 3.97, 95% CI 1.39-13.2). Adenocarcinoma was the only histological type reported, with programmed death ligand-1 expression ≥1% in tumour cells in three samples. Cancer staging was localised (I/II) in eight (40%) individuals, locally advanced (III) in two (10%) and metastatic (IV) in 10 (50%). We found no somatic variant eligible for targeted therapy. Seven cancers were surgically removed, 10 received systemic therapy, and three received the best supportive care according to their stage and performance status. The median overall survival was 24 months, with stage I/II cancers showing better survival. We identified 233 TRG variant carriers. The comparative risk (subdistribution hazard ratio) for lung cancer in SRG patients versus TRG patients was 18.1 (95% CI 7.1-44.7).

CONCLUSIONS

The high risk of lung cancer among SRG variant carriers suggests specific screening and diagnostic and therapeutic challenges. The benefit of regular computed tomography scan follow-up should be evaluated.

Short peripheral blood leukocyte telomere length in rheumatoid arthritis-interstitial lung disease

Shortened telomere lengths (TLs) can be caused by single nucleotide polymorphisms and loss-of-function mutations in telomere-related genes (TRG), as well as ageing and lifestyle factors such as smoking. Our objective was to determine if shortened TL is associated with interstitial lung disease (ILD) in individuals with rheumatoid arthritis (RA). This is the largest study to demonstrate and replicate that shortened peripheral blood leukocytes-TL is associated with ILD in patients with RA compared with RA without ILD in a multinational cohort, and short PBL-TL was associated with baseline disease severity in RA-ILD as measured by forced vital capacity percent predicted.

Lung transplantation outcome in adult surfactant-related interstitial lung disease: first evidence to move on

A new study reports the first evidence to "move on" with lung transplantation in adult surfactant-related fibrotic ILDs. It highlights the need for better genetic characterisation of transplant candidates and cancer screening for these patients. https://bit.ly/3QxG73Z.

Genetic and environmental factors in interstitial lung diseases: current and future perspectives on early diagnosis of high-risk cohorts

Within the wide scope of interstitial lung diseases (ILDs), familial pulmonary fibrosis (FPF) is being increasingly recognized as a specific entity, with earlier onset, faster progression, and suboptimal responses to immunosuppression. FPF is linked to heritable pathogenic variants in telomere-related genes (TRGs), surfactant-related genes (SRGs), telomere shortening (TS), and early cellular senescence. Telomere abnormalities have also been identified in some sporadic cases of fibrotic ILD. Air pollution and other environmental exposures carry additive risk to genetic predisposition in pulmonary fibrosis. We provide a perspective on how these features impact on screening strategies for relatives of FPF patients, interstitial lung abnormalities, ILD multi-disciplinary team (MDT) discussion, and disparities and barriers to genomic testing. We also describe our experience with establishing a familial interstitial pneumonia (FIP) clinic and provide guidance on how to identify patients with telomere dysfunction who would benefit most from genomic testing.

European Respiratory Society statement on familial pulmonary fibrosis

Genetic predisposition to pulmonary fibrosis has been confirmed by the discovery of several gene mutations that cause pulmonary fibrosis. Although genetic sequencing of familial pulmonary fibrosis (FPF) cases is embedded in routine clinical practice in several countries, many centres have yet to incorporate genetic sequencing within interstitial lung disease (ILD) services and proper international consensus has not yet been established. An international and multidisciplinary expert Task Force (pulmonologists, geneticists, paediatrician, pathologist, genetic counsellor, patient representative and librarian) reviewed the literature between 1945 and 2022, and reached consensus for all of the following questions: 1) Which patients may benefit from genetic sequencing and clinical counselling? 2) What is known of the natural history of FPF? 3) Which genes are usually tested? 4) What is the evidence for telomere length measurement? 5) What is the role of common genetic variants (polymorphisms) in the diagnostic workup? 6) What are the optimal treatment options for FPF? 7) Which family members are eligible for genetic sequencing? 8) Which clinical screening and follow-up parameters may be considered in family members? Through a robust review of the literature, the Task Force offers a statement on genetic sequencing, clinical management and screening of patients with FPF and their relatives. This proposal may serve as a basis for a prospective evaluation and future international recommendations.

Genetics of human telomere biology disorders

Telomeres are specialized nucleoprotein structures at the ends of linear chromosomes that prevent the activation of DNA damage response and repair pathways. Numerous factors localize at telomeres to regulate their length, structure and function, to avert replicative senescence or genome instability and cell death. In humans, Mendelian defects in several of these factors can result in abnormally short or dysfunctional telomeres, causing a group of rare heterogeneous premature-ageing diseases, termed telomeropathies, short-telomere syndromes or telomere biology disorders (TBDs). Here, we review the TBD-causing genes identified so far and describe their main functions associated with telomere biology. We present molecular aspects of TBDs, including genetic anticipation, phenocopy, incomplete penetrance and somatic genetic rescue, which underlie the complexity of these diseases. We also discuss the implications of phenotypic and genetic features of TBDs on fundamental aspects related to human telomere biology, ageing and cancer, as well as on diagnostic, therapeutic and clinical approaches.

Genetics in Idiopathic Pulmonary Fibrosis: A Clinical Perspective

BACKGROUND

Unraveling the genetic background in a significant proportion of patients with both sporadic and familial IPF provided new insights into the pathogenic pathways of pulmonary fibrosis.

AIM

The aim of the present study is to overview the clinical significance of genetics in IPF.

PERSPECTIVE

It is fascinating to realize the so-far underestimated but dynamically increasing impact that genetics has on aspects related to the pathophysiology, accurate and early diagnosis, and treatment and prevention of this devastating disease. Genetics in IPF have contributed as no other in unchaining the disease from the dogma of a "a sporadic entity of the elderly, limited to the lungs" and allowed all scientists, but mostly clinicians, all over the world to consider its many aspects and "faces" in all age groups, including its co-existence with several extra pulmonary conditions from cutaneous albinism to bone-marrow and liver failure.

CONCLUSION

By providing additional evidence for unsuspected characteristics such as immunodeficiency, impaired mucus, and surfactant and telomere maintenance that very often co-exist through the interaction of common and rare genetic variants in the same patient, genetics have created a generous and pluralistic yet unifying platform that could lead to the understanding of the injurious and pro-fibrotic effects of many seemingly unrelated extrinsic and intrinsic offending factors. The same platform constantly instructs us about our limitations as well as about the heritability, the knowledge and the wisdom that is still missing.

Compound heterozygous mutation of RTEL1 in interstitial lung disease complicated with pneumothorax and emphysema: A case report and literature review

Interstitial lung diseases (ILDs) are common respiratory diseases with limited treatment options and poor prognoses. Early and accurate diagnosis of ILD is challenging and requires a multidisciplinary discussion. We report a 32-year-old patient admitted to our hospital with cough and increasing dyspnea on exertion. Computerized tomography scan of his chest demonstrated diffuse interstitial abnormalities, emphysematous changes, and a pneumothorax. Whole-exome sequencing (WES) and Sanger sequencing indicated a compound mutation of heterozygosity in RTEL1 gene c.2992C > T(p.Arg998*) and c.482T > C(p.Val161Ala). In-silicon analysis revealed the pathogenic nonsense mutation c.2992C > T, which introduced a premature stop codon in exon 30 of RTEL1. The patient is still alive with progressive dyspnea to now. We reviewed the pathophysiology of ILD patients carrying RTEL1 mutations and the roles of RTEL1 mutation in guiding treatment and prognostication in ILD.

Interstitial lung diseases associated with mutations of poly(A)-specific ribonuclease: A multicentre retrospective study

BACKGROUND AND OBJECTIVE

Poly(A)-specific ribonuclease (PARN) mutations have been associated with familial pulmonary fibrosis. This study aims to describe the phenotype of patients with interstitial lung disease (ILD) and heterozygous PARN mutations.

METHODS

We performed a retrospective, observational, non-interventional study of patients with an ILD diagnosis and a pathogenic heterozygous PARN mutation followed up in a centre of the OrphaLung network.

RESULTS

We included 31 patients (29 from 16 kindreds and two sporadic patients). The median age at ILD diagnosis was 59 years (range 54 to 63). In total, 23 (74%) patients had a smoking history and/or fibrogenic exposure. The pulmonary phenotypes were heterogenous, but the most frequent diagnosis was idiopathic pulmonary fibrosis (n = 12, 39%). Haematological abnormalities were identified in three patients and liver disease in two. In total, 21 patients received a specific treatment for ILD: steroids (n = 13), antifibrotic agents (n = 11), immunosuppressants (n = 5) and N-acetyl cysteine (n = 2). The median forced vital capacity decline for the whole sample was 256 ml/year (range -363 to -148). After a median follow-up of 32 months (range 18 to 66), 10 patients had died and six had undergone lung transplantation. The median transplantation-free survival was 54 months (95% CI 29 to ∞). Extra-pulmonary features were less frequent with PARN mutation than telomerase reverse transcriptase (TERT) or telomerase RNA component (TERC) mutation.

CONCLUSION

IPF is common among individuals with PARN mutation, but other ILD subtypes may be observed.