The aim of the study is to assess the number of patients with elevated blood tryptase for whom this elevation could be linked to a hereditary alpha-tryptase secretion abnormality or hyper-alpha-tryptasemia. This information will enable to better optimize the management and follow-up of patients who have experienced hypersensitivity reactions and have elevated basal blood tryptase levels. The patients will be offered the opportunity to take part in the study. If they consent to participate, they will be tested for hereditary hyper-alpha-tryptasemia. A blood sampling will be performed in the center. A few weeks after, the patient will be informed about the blood sample result during a medical consultation organized in the center.

Inclusion Criteria:

• Patients who came in the pneumoallergology department of the CHU de Nice since January 2014 for an allergological workup
• Patients who have received at least one basal tryptase assay, according to recommendations
• informed consent signature

Exclusion Criteria:

• High tryptasemia (≥ 8ng/ml) synchronous with anaphylactic reaction and unconfirmed basally
• Known diagnosis of systemic mastocytosis