DDAH2 and Sepsis: The DDAH2 gene is located in the major histocompatibility complex (MHC)III region of chromosome 6 and DDAH2 is the only isoform found in immune cells [24]; DDAH1 by contrast, the gene that is found on chromosome 1, is an important regulator of vascular function and has been shown to modulate the haemodynamic response in animal models of sepsis [30, 31].