Of them, 265 (16) patients had serum AAT levels between 60 mg/dL and 116 mg/dL (might be considered an intermediate AATD) with a mean plasma AAT level of 98.9 (SD 14.2) mg/dL, while 66 (4% of those tested) patients had serum AAT levels < 60 mg/dL (a severe AATD) with a mean plasma AAT level of 19.3 (SD 14.6) mg/dL (Figure 2). The gene discussed is SERPINA1; the disease is alpha 1-antitrypsin deficiency.