Proposed classification of paediatric PAP
| Category of disease | Exemplar conditions |
| Disorders of surfactant protein metabolism | SFTPB, STFPC, ABCA3 and TTF1 mutations |
| GM-CSF receptor gene mutations | α- and β-chain mutations |
| Other genetic disorders | MARS, STING, COPA and GATA2 mutations |
| Metabolic disease | Lysinuric protein intolerance, Niemann–Pick disease |
| Associated with immune deficiency | |
| Congenital | SCID, ADA deficiency |
| Acquired | HIV, leukaemia |
| Associated with connective tissue disease | Idiopathic juvenile chronic arthritis |
| Miscellaneous | Congenital heart disease |
| Diseases seen in adults | |
| Exclusively in adults | Macrophage blockade, lymphoma |
| Mainly in adults | Autoimmune |
GM-CSF: granulocyte–macrophage colony-stimulating factor; STFPB: surfactant protein B; STFPC: surfactant protein C; ABCA3: ATP-binding cassette 3; TTF1: thyroid transcription factor 1; MARS: methionyl transfer RNA synthetase; STING: stimulator of interferon; COPA: non-clathrin-coated vesicular coat protein A; GATA2: GATA-binding protein 2; SCID: severe combined immunodeficiency; ADA: adenosine deaminase.