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

Poly(A)-specific ribonuclease (PARN) mutations have been associated with familial pulmonary fibrosis. However, the phenotype of patients with interstitial lung disease (ILD) and PARN mutations is poorly described. We performed a retrospective, observational, non-interventional study. All the patients with an ILD diagnosis and a pathogenic heterozygous PARN mutation, followed in one of the OrphaLung center, were included. We included 30 patients (24 patients from 11 kindreds and 6 sporadic patients with early onset of ILD or extra-pulmonary phenotype). The median age at diagnosis of ILD was 59 years (range 54 - 64). Twenty-three patients (77 %) had a smoking history and/or a fibrogenic exposure. The pulmonary phenotypes were heterogenous but the most frequent diagnosis was idiopathic pulmonary fibrosis (IPF; n=15, 50%). Hematological abnormalities were identified in 3 patients and liver disease in 2 patients. Twenty-one patients received a specific treatment for ILD: steroids (n=13), antifibrotic (n= 11), immunosuppressants (n=5) and N-acetyl cysteine (n=2). The median decline of FVC for the whole population was 292 ml/year (range 146 - 657). After a median follow-up of 2.8 years 8 patients had died and 6 had undergone lung transplantation. The median transplantation-free survival was 4.5 years. PARN mutation carriers were older, and extra-pulmonary manifestations were less frequent as compared to TERT or TERC mutation carriers. PARN mutations are most frequently associated with IPF, but other ILD may be observed. Such phenotypic heterogeneity requires a thorough evaluation of PARN-associated ILD patients in order to define tailored therapeutic strategies.