The prevalence of fish, seafood and Anisakis allergy varies greatly depending on country-specific eating habits, assuming that the highest consumption corresponds to the highest prevalence. Mediterranean countries are particularly affected.

Hereditary Alpha-Tryptasemia (HaT) is a common autosomal dominant genetic trait recently identified. Although it is estimated to affect approximately 1 in 20 individuals of white European origin, a diagnostic method is not routinely available.

Here by we present the cases of two families with different allergic reaction phenotypes to fish and seafood, IgE and no IgE mediated reactions. The current review focused on the impact of the diagnosis of HaT in families, particularly when the mutation is symptomatic and the affectation from an early age and in both sexes and finally this review tried to warn about the possible involvement of Anisakis in allergic reactions in patients with HaT.