Pairwise LD (D') measured by means of Arlequin confirmed the existence of LD among several SNPs at SFTPA1 and SFTPA2, whereas SFTPD aa11 was only observed in LD with SFTPA1 aa19 (see Figure 1) . A similar pattern of LD was observed when D' was measured by means of the Haploview software (data not shown). SFTPA1 and SFTPA2 were previously found to be in LD [25, 26] . The value of LD measured as r 2 was very low for every pair of SNPs (data not shown), and none of the studied SNPs could be used as haplotypetagging SNP to infer the observed haplotypes. When pairwise LD was measured among haplotypes instead among SNPs, SFTPA1 was found to be in LD with SFTPD aa11, but only a marginal LD was found between SFTPA2 1A and SFTPD aa11 (see Table E3 in Additional File 1).