This study is unique in reporting a genetic association between non-synonymous SNPs at SFTPD, SFTPA1 and SFTPA2, as well as of haplotypes encompassing these genes, with the susceptibility, severity and outcome of CAP. The major alleles of SFTPA1 aa50-G, aa219-C as well as SFTPA2 aa9-A and aa91-G or genotypes carrying these alleles were associated with protection against CAP. The frequencies of the different SNPs and haplotypes of SFTPA1, SFTPA2 and SFTPD observed in our study were similar to those previously reported in European populations [25] . SFTPA1 and SFTPA2 were reported to be in strong LD [26, 27] , and several haplotypes of these loci tend to segregate together, being 6A 2 -1A 0 the major haplotype [27] . A protective role against CAP was associated with 6A 2 , 1A 0 and 6A 2 -1A 0 in our survey but only the rare 1A 10 and 6A 3 -1A haplotypes were significantly associated with susceptibility to CAP. Similar results were observed in susceptibility to pneumococcal CAP. Several SNPs and Table 4 . [15] . † P-value for the bivariate comparison. ‡ P-value for multivariate analysis, including the variables age, gender, hospital of origin and co-morbidities. For those bivariate comparisons that resulted in nonsignificant differences, multivariate analysis were not calculated. § P-value for multivariate analysis, including the variables hospital of origin, PSI (Pneumonia Severity Index) and pathogen. haplotypes were also associated with a higher severity and poor outcome; MODS, ARDS, and mortality were selected because they represent the more severe clinical phenotypes. Particularly, 1A 10 and 6A-1A were overrepresented among patients who died at 28 or 90 days, and they also predisposed to MODS and ARDS respectively. Likewise, 6A was associated with ARDS, and 1A was associated with MODS. By contrast, 6A 3 and 6A 3 -1A 1 were underrepresented in patients who died. The SFTPD aa11-C allele was associated with the development of MODS and ARDS, but no significant effects on mortality were observed. In spite that the power of the test for some associations with outcome and severity were higher than 80% for the observed OR with a significance level of 5%, the number of individuals included in the analysis of outcome was relatively small. Consequently, associations with outcome should be interpreted with caution.