Previous study showed that serum levels of SP‐D in RP patients were elevated.22, 23, 24 More specifically, the genetic polymorphisms in SP‐D were associated with some lung injuries such as COPD,25 interstitial pneumonia,26 asthma,27 lung cancer,26 and infectious lung diseases.28, 29 Therefore, we suspected that single–nucleotide polymorphisms (SNPs) of SP‐D would also be associated with RP. This evidence concerns the gene SFTPD and lung carcinoma.