All patients with primary eosinophilia (CEL, HES and systemic mastocytosis) were negative for the C-KIT-D816V mutation, while cytogenetic analysis in all, but one patient (case 2 of Table 1), due to dry-tap on bone marrow aspiration, was normal. The gene discussed is KIT; the disease is Chronic Eosinophilic Leukemia, Not Otherwise Specified.