The role of omalizumab, a monoclonal anti-IgE antibody that binds to free IgE and reduces the expression of FcεRI on MCs and basophils, was discussed in the management of selected individuals with HαT who suffer from severe, IgE-dependent, allergies or secondary (IgE-mediated) MCAS. This evidence concerns the gene TMPRSS11D and Allergy.