Interestingly, a study performed on patients affected by systemic mastocytosis (SM) and grouped into SM with (SM+C) or without (SM-C) additional cutaneous lesions evidenced that the two SM forms were distinguished by the lower levels of PRP-3, PRP-3 desArg106, statherin desPhe43, P-B des1–5, and cystatin D des1–5 and des1–8 in SM-C patients with respect to SM+C [74]. The gene discussed is CST5; the disease is systemic mastocytosis.