Representative expression of alternative transcripts in blood samples detected by RT-PCR. a Schematic graphic of the structure of the SERPINA1 gene. Primers used for RT-PCR expression analysis are represented by arrows. RT-PCR expression analysis in leukocytes from peripheral blood samples showed evidence for different alternative splicing event occurring within noncoding exons 1A, 1B and 1C of SERPINA1 gene. b Amplification fragment corresponding to the expression in blood samples detected using a forward primer in exon 1A and a reverse primer in exon 2. A single band of 633 bp was detected which corresponded to a transcript containing exon 1A joined directly to exon 2. c Bands detected by using forward primer 1B. Different expression fragments were detected corresponding to splicing variants. The structure of these splicing variants has been described in detail before . Three different bands are clearly visualized due to the different splicing sites used within exons 1B and 1C. The band of 712 bp corresponded to the exon 1B joined to exon 2. The band of 816 bp corresponded to an isoform containing both exons 1B and 1C. The upper band of 971 corresponds to a fragment with retained intron in between exons 1B and 1C. d Using a forward primer in the exon 1C a single band of 587 bp was amplified.