CSF2RA and autoimmune pulmonary alveolar proteinosis: While rare mutations in the GM-CSF receptor α or β chains (CSF2RA, CSF2RB)8, the surfactant proteins B or C9, ATP-binding cassette subfamily A member 3 (ABCA3)10, and thyroid transcription factor-111 were identified as causing hereditary PAP, the genetic basis underlying autoimmune PAP (aPAP) has never been thoroughly investigated due to its low prevalence.