The SFTPB SNP (rs7316) that is significant by itself in mild CF after Bonferroni correction was the only SFTPB SNP that interacted with SNPs of SFTPA1 or SFTPA2, whereas the SNP-SNP intergenic interactions between SFTPB and SFTPD include three of the four SFTPB SNPs studied. Here, SFTPA2 is linked to cystic fibrosis.