Transcription analyses of SERPINA1 transcripts in human tissues. Relative expression levels of 1A, 1B and 1C transcripts in 16 human tissues is shown. Specific patterns of transcript expression were detected in different tissues. Leukocytes exhibited higher expression levels of transcripts 1A, 1B, and 1C when compared to other tissues. The 1A transcript was found predominantly in leukocytes and lung tissue. Specific expression of 1C transcripts were detected in lung, liver, kidney or pancreas, suggesting that transcription in these tissues start in the transcription site located in exon 1C. Expression of 1B transcripts were almost exclusively detected in leukocytes.