SP-B is encoded by SFTPB, a single, 11425 nucleotide long gene on chromosome 2. Mutations in this gene are the basis for several of the lung conditions mentioned above.  Both frameshift mutations and several single nucleotide polymorphisms (SNPs) have been found correlated to a variety of lung conditions. A frame shift mutation responsible for congenital alveolar proteinosis (CAP) was identified by Kattan et al. Many SNP's have been identified in relation to lung conditions. They have been correlated to severe influenza, neonatal respiratory distress syndrome, mechanical ventilation necessity, and more.