TPSAB1 and digestive system disorder: Other gene mutations concern tpsab1, a gene encoding for alpha-tryptase, whose high levels were found in patients with symptoms easily found in hEDS patients (such as connective tissue abnormalities, autonomic dysfunction, gastrointestinal disorders, allergic, and cutaneous symptoms), although not all patients with tpsab1 mutations met diagnostic criteria for hEDS and elevated alpha-tryptase basal serum levels are quite common in the general population [63].