TMPRSS11D and anaphylaxis: In order to validate this association, two large cohorts of venom allergic patients from Italy and Slovenia were tryptase-genotyped, and in both cohorts, the prevalence of HαT among individuals with severe HVA (grade IV on the Mueller scale) was found to be at least twice that of the general population and that of those with less severe anaphylaxis (grades I–III) [84].