Alpha1-antitrypsin deficiency is an autosomal recessive disease characterized by reduced serum levels of alpha1-antitrypsin (AAT) due to mutations in the SERPINA1 gene causing early onset pulmonary emphysema and, occasionally, chronic liver disease. We report an incidental finding of a novel null AAT allele, Q0Milano, consisting of a 17 nucleotides deletion in exon 3 of SERPINA1 gene, in an Italian child with persistently increased liver enzymes, a mild decrease in circulating AAT levels and without any pulmonary disease. Q0Milano variant results in an unfunctional protein lacking of AAT active site, as the resultant protein is truncated near PiS locus involved in AAT protein stability
