In conclusion, in the present study we describe a novel association between a genetic polymorphism in the NFKBIA gene and susceptibility to P-CAP in adult Caucasian patients and we find evidence that genetic variants from key cytokines of the innate immune response (Il-4, IL-10, IL-R1 and IL-12B) and NF-κB inhibitors are associated with the presence of severe CAP, respiratory failure or higher punctuations in CURB-65 or PSI scores in patients with P-CAP. This evidence concerns the gene NFKB1 and respiratory failure.