Testing is available for

ILDs related to alveolar surfactant region
Surfactant-Protein-B Deficiency (Mutations in SFTPB)
Surfactant-Protein-C Deficiency (Mutations in SFTPC)
ABCA3-Deficiency (Mutations in ABCA3)
Brain Lung Thyroid Syndrome (Mutations in TTF1)
Congenital Pulmonary Alveolar Proteinosis (Mutations in CSFR2A, CSFR2B)

Diffuse developmental disorder
Alveolar Capillary Dysplasia (Mutations in FoxF1)

Idiopathic pulmonary fibrosis
Mutations in telomerase reverse transcriptase (TERT)
Mutations in telomerase RNA component (TERC)
Mutations in the regulator of telomere elongation helicase 1 (RTEL1)
Mutations in poly(A)-specific ribonuclease (PARN)

Treatment
ILD is not a single disease but encompasses many different pathological processes. Hence treatment is different for each disease. If a specific occupational exposure cause is found, the person should avoid that environment. If a drug cause is suspected, that drug should be discontinued.Many cases due to unknown or connective tissue-based causes are treated with corticosteroids, such as prednisolone. Some people respond to immunosuppressant treatment. Oxygen therapy at home is recommended in those with significantly low oxygen levels.Pulmonary rehabilitation appears to be useful with the benefits being sustainable longer term with improvement in exercise capacity, dyspnoea, and quality of life. Lung transplantation is an option if the ILD progresses despite therapy in appropriately selected patients with no other contraindications.On October 16, 2014, the Food and Drug Administration approved a new drug for the treatment of Idiopathic Pulmonary Fibrosis (IPF). This drug, Ofev (nintedanib), is marketed by  Boehringer Ingelheim Pharmaceuticals, Inc. This drug has been shown to slow the decline of lung function although the drug has not been shown to reduce mortality or improve lung function. The estimated cost of the drug per year is approximately $94,000. References
19.
Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of respiratory diseases affecting the interstitium (the tissue and space around the alveoli (air sacs)) of the lungs. It concerns alveolar epithelium, pulmonary capillary endothelium, basement membrane, and perivascular and perilymphatic tissues. It may occur when an injury to the lungs triggers an abnormal healing response. Ordinarily, the body generates just the right amount of tissue to repair damage, but in interstitial lung disease, the repair process is disrupted, and the tissue around the air sacs (alveoli) becomes scarred and thickened. This makes it more difficult for oxygen to pass into the bloodstream. The disease presents itself with the following symptoms: shortness of breath, nonproductive coughing, fatigue, and weight loss, which tend to develop slowly, over several months. The average rate of survival for someone with this disease is between three and five years. The term ILD is used to distinguish these diseases from obstructive airways diseases. There are specific types in children, known as childrens interstitial lung diseases. The acronym ChILD is sometimes used for this group of diseases.Prolonged ILD may result in pulmonary fibrosis, but this is not always the case. Idiopathic pulmonary fibrosis is interstitial lung disease for which no obvious cause can be identified (idiopathic) and is associated with typical findings both radiographic (basal and pleural-based fibrosis with honeycombing) and pathologic (temporally and spatially heterogeneous fibrosis, histopathologic honeycombing, and fibroblastic foci). In 2015, interstitial lung disease, together with pulmonary sarcoidosis, affected 1.9 million people.