A correlation between polymorphisms in HLA-G gene and the condition of severely ill patients with SS has been found [28], with evidence identifying that patients with severe sepsis due to pneumonia are more likely to suffer from SS when carrying the 4G allele of PAI-1 polymorphism and poor prognosis of septic patients has been related to the polymorphism of interleukin-1 receptor antagonist (ILRN) 2 [26,29]. This evidence concerns the gene IL1RN and pneumonia.