Of the 29 interactions associated with increased HP risk, we observed (a) one intragenic interaction among SNPs of the SFTPA1 (rs1059047 x rs1136450 x rs1136451), where each SNP exhibited a dominant effect, p = 0.03, OR = 1.9 (1.2–3) (shown in Figure 1), and the remaining 28 interactions were intergenic. This evidence concerns the gene SFTPA1 and hypersensitivity pneumonitis.