In four patients (mean age 52 years) with severe osteoporosis and mastocytosis confirmed by bone marrow biopsy (over 40 mast cells/mm3), the following protocol was applied: interferon alpha (IFN) 3 million units (MU) three times a week, reduced to 1.5 MU three times a week in case of intolerance, and pamidronate (Pam) 90 mg/month as an infusion. This evidence concerns the gene IFNA1 and mastocytosis.