β2-microglobulin (β2m) causes a iatrogenic form of systemic amyloidosis when associated to long term haemodialysis1 and is associated with a familial form of the disease in the presence of the D76N mutation, characterized by progressive bowel disfunction and extensive amyloid deposits in the spleen, liver, heart, salivary glands and nerves2. This evidence concerns the gene B2M and primary systemic amyloidosis.