The worldwide frequency of AATD varies according to population and is particularly prevalent in Europe with multiple studies reporting a high prevalence of the deficiency alleles in Poland,19,20 France,21 Italy22 and Ireland.23 AATD is characterized by circulating levels <11 μmol/L, which is the putative protective threshold level.24 The AAT phenotype is determined by codominant expression of parental alleles with the majority of individuals carrying 2 copies of non-mutated M allele. Here, SERPINA1 is linked to alpha 1-antitrypsin deficiency.