ACE2 and acute respiratory distress syndrome: More importantly, the locus that modulates body weight loss at 2 and 3 dpi is co-located precisely with the location of Ace2 on distal Chr X. These results strongly suggest that Ace2 polymorphisms, or perhaps different isoforms as in humans (54), are linked to H1N1 disease progression, and that lower levels of Ace2 may play a role in virus-induced ALI.