Fig. 7

Sanger Sequencing results of 'Retention of the first 140 bases of intron 1' RT-PCR bands from three exon 1 terminal variants (c.56G > A/C/T) in SPINK1. Refer to Fig. 6 for the corresponding bands. Each band was found to contain a mixture of aberrantly spliced and normally spliced transcripts, with the 5’ and 3’ junctions of the aberrant transcript isoform, being delineated by vertical lines. The annotations beneath the electropherograms detail the junction-spanning sequences for both isoforms: the upper annotation for the aberrantly spliced transcript and the lower for the normally spliced transcript. In all subpanels, the normally spliced transcripts show a consistent sequence of exon 1 followed by exon 2, with the introduced exon 1 terminal variants highlighted in red. The aberrantly spliced transcripts have consistent 5’ junctions with exon 1 followed by intron 1 sequences (introduced variants in red), and their 3’ junctions are uniform, displaying retained intron 1 sequence (up to c.55 + 140) followed by exon 2. Sequence numbering is based on NM_001379610.1. Specifically, c.55 and c.56 denote the terminal position of exon 1 and the start of exon 2 in SPINK1, respectively; c.55 + 1 and c.55 + 140 refer to the first and the 140th nucleotides of intron 1 in SPINK1. Abbreviations: RT-PCR, reverse transcription-PCR