ACE2 and severe acute respiratory syndrome: No differences in allele frequencies between the different groups were detected and it was concluded that, despite its X-chromosome location, poor outcomes in male SARS patients do not appear to be related to genetic variants of ACE2. Similarly, in another case–control study involving 44 SARS cases, 16 anti-SARS-CoV antibody-positive contacts, 87 antibody-negative contacts and 50 non contacts in Vietnam, no evidence emerged that the ACE2 gene polymorphisms are involved in the disease process in this population.