Hydroxychloroquine in Children's Interstitial Lung Diseases With Genetic Causes

Inclusion Criteria: * A clinical diagnosis of chILD with age\<18 years * Genetically diagnosed (e.g. SFTPC, SFTPB, ABCA3, NKX2-1, CSF2RA, CSF2RB, IARS, MARS, COPA, SLC7A7, LRBA) * Patients have to be clinically stable with no major changes in their medication in the last 4 weeks * No HCQ treatment in the last 12 weeks * Signed and dated informed consent of the subject (if subject has the ability) and the representatives (of underaged children) must be available before start of any specific trial procedures Exclusion Criteria: * Acute severe infectious exacerbations * Known hypersensitivity to HCQ, or other ingredients of the tablets * Proven retinopathy or maculopathy * Renal insufficiency at screening, defined as glomerular filtration rate (GFR)\< 40 mL/min/1.73 m2 in patients aged 3 to 8 weeks\< 60 mL/min/1.73 m2 in patients ≥ 8 weeks of age * Participation in other clinical trials during the present clinical trial