The cause of most interstitial lung diseases (ILDs) is still unknown. Further research, for example to determine predisposing genetic factors, is therefore needed. A database with relevant clinical data and DNA/serum samples of ILD patients could facilitate future research on the cause of ILDs.

Protocol title: 'Registration of clinical data and DNA of patients with Interstitial Lung Disease (ILD)' Rationale: The etiopathogenesis of most Interstitial Lung Diseases (ILDs) is still unknown. Further research, e.g. to determine predisposing genetic factors, is therefore needed. A database with relevant clinical data and DNA/serum samples of ILD patients could facilitate future research on the etiopathogenesis of ILDs.

Objective: Availability of relevant clinical data and DNA/serum samples of ILD patients in a database. Those data can be used for future research.

Study design: A prospective observational study

Study population: Patients diagnosed with ILD attending the pulmonology department in participating hospitals.

Intervention: a blood sample is taken from each patient. Furthermore, additional information is collected from the medical file.

Main study parameters/endpoints: DNA and serum sample, demographic variables, medical information, occupational history and hobbies.

Nature and extent of the burden and risks associated with participation, group relatedness: two tubes of blood will be drawn from the patients. The risks of drawing blood from a vein are minimal.

Inclusion Criteria:

• Diagnosis of an ILD, as stated by the American Thoracic Society (ATS)