IGHA1 and triple-A syndrome: In addition, immunoglobulins A1 and A2 (IGA1 and IGA2) plasma levels were analyzed by turbidimetry in a pilot study [controls (n = 22) and AAA patients (n = 22)] and in a validation study with a 6-year follow-up [controls (n = 64) and AAA patients (n = 189)].