Hereditary Alpha-Tryptasemia and Mastocytosis: What We Know and What We Need To Learn

This review aims to elucidate the evolving relationship between hereditary alpha-tryptasemia (HαT) and mastocytosis, emphasizing recent advances in understanding shared pathophysiological mechanisms, diagnostic challenges, and clinical implications. HαT is a common genetic trait caused by increased copy numbers of the TPSAB1 gene encoding alpha-tryptase. It accounts for most elevated serum baseline tryptase (SBT) levels (> 8 ng/mL) seen in clinical allergy practice. Diagnosis is established through tryptase genotyping—often referred to as “tryptase copy number variation (CNV) testing”. Over the past decade, studies have reported a high prevalence of HαT among individuals with mastocytosis, prompting routine screening. However, the nature of this association remains controversial. While some studies suggest a potential link—most notably an increased risk of severe anaphylaxis—others have failed to show consistent correlations in pathophysiology or clinical outcomes. The evidence base is still evolving, and inconsistencies across studies underscore the need for cautious interpretation. HαT complicates the clinical assessment of mastocytosis by influencing baseline tryptase levels and potentially modulating symptom severity, though its clinical impact remains under investigation. Further research is needed to clarify the extent and nature of HαT’s contribution to mastocytosis and related mast cell disorders.