The concerned patients are children and adults suffering from idiopathic interstitial pneumonias, other chronic fibrosing interstitial pneumonias with a progressive phenotype, and interstitial pneumonia associated with Scleroderma and related cases of patients carrying a mutation on one of the telomere-associated genes.

This is a national, observational, longitudinal, multicenter study that will be conducted retrospectively and prospectively. It aims to collect consistent and comparable clinical data for patients and their relatives, whether they carry a mutation or not, affected by diffuse idiopathic interstitial pneumopathy.

The expected duration of the study, including data analysis, is approximately 10 years (5 years for participant enrollment and 5 years of follow-up, in addition to the steps for data management and statistical analyses).

Each participating center will inform every participant by providing an information sheet, and their written consent will be obtained before including them in the study and commencing data collection.

Prospective medical data will be collected at 6 months to 1 year after enrollment and then at least once per year for patients up to 5 years and 5 years for their relatives.

Participants will complete a self-questionnaire during their regular follow-up consultations or by accessing a secure interface.

Inclusion Criteria:

Confirmed diagnosis of IIP established based on clinical, radiological, or functional criteria.

Confirmed diagnosis of non-IPF progressive fibrotic interstitial lung disease (PF-ILD) with fibrosis ≥ 10% on CT scan, disease worsening not related to pulmonary embolism, decompensated heart failure, or lower respiratory tract infection, and disease progression despite "appropriate management" evaluated over a period of up to 24 months:

• A relative decline in Forced Vital Capacity (FVC) of at least 10% from predicted value, with or without clinical deterioration, or
• A combination of at least 2 of the following criteria: a relative decline in FVC between 5% and 10% from predicted value, worsening respiratory symptoms, increased extent of pulmonary fibrosis on thoracic CT scan.

Confirmed diagnosis of Systemic Sclerosis-associated Interstitial Lung Disease (SSc-ILD) (American College of Rheumatology criteria), with a total score ≥ 9 and disease extent involving ≥ 10% of the lungs (defined by reticular abnormalities, honeycombing, and ground-glass opacities) on high-resolution CT (HRCT) scan.

For relatives: First degree relatives of patients carrying a mutation in TERT, TERC, RTEL1, TINF2, DKC1, PARN genes, and other telomere related genes that may be described in the future and included.

The study cohort will include:

• Prevalent and incident cases of symptomatic adult and paediatric patients with a diagnosed IIP, other chronic fibrosing ILDs with progressive phenotype, SSc-associated ILDs. In total, 2850 patients are expected. 1600 patients are already included via the initial protocol RaDiCo-PID.
• Cases corresponding to patients included as 1st degree relatives of a symptomatic diagnosed FPF patient carrying a specific mutation. About 150 relatives are expected in this protocol. No inclusion in initial protocol because it is a new population.