Alkaptonuria is a novel human secondary amyloidogenic disease

► Alkaptonuria (no therapy) is a novel type II secondary amyloidosis. ► Ochronotic melanin-based pigment and SAA/SAP amyloid co-localize in Alkaptonuria. ► High levels of SAA and SAP were found in AKU patients' plasma. ► Systemic amyloidosis was assessed in patients' abdominal fat and salivary gland. ► Methotrexate reduces (- 97%) HGA-induced A-amyloid aggregates.