Representation of SERPINA1 gene and QT-PCR assays. a Schematic representation of the SERPINA1 gene exons with non-coding exons (1A, 1B and 1C) and exons 2–5 coding for the AAT protein. Numbers above the non-coding and coding exons represent the intron length in bp. Locations of the different primers used for the three QT-PCR assays were represented by arrows. b Different alternative transcripts occur in the AAT gene by alternatively splicing of the non-coding exons 1A, 1B and 1C and the use of the different transcription start sites. Five transcripts (I, II, III, IV and V) can be detected with any of the assays (1A, 1B and 1C). The exon structure of these transcripts corresponds to isoforms found in Ensembl database listed in the Figure. Additionally, another transcript structure (IV), generated by transcription from exon 1B, is not represented in Ensembl database but transcription from exon 1B have been described in the literature [8–10].