is Figure S1 Showing primer design to span BRCA1 cDNA. Primers indicated by arrows positioned on exon 1 and exon 24. Full-length transcript is 7.2 kb. Length of full length amplicon is 5.8 kb. Figure S2 showing results from 47 BRCA1 RT-PCR assays. 2 μl of each reaction was visualised on a 1% agarose gel. Samples that underwent MinION sequencing in Sample 1 or Sample 2 are indicated, and long-range PCR reactions where we confirmed fragments were specific to BRCA1 by Sanger sequencing. 2 μl of each reaction was run on 1% agarose gels. A Protocol 1. B Protocol 2. C Protocol 3. Primer annealing temperature indicated above each lane. Reference markers labelled for size in base pairs. Figure S3 showing a schematic of the nanopore sequencing read filtering steps applied in the study. Figure S4 showing sequencing of the full-length BRCA1 Δ10-17 isoform. Integrated Genome Viewer (IGV) screenshots shown for the whole gene, along with close-up views of exons 9 and 18 (also highlighted by black triangles). BRCA1 exons are indicated and represented as blue solid rectangles. Each MinION sequence read with perfect homology to the reference sequence is shown in grey. Mismatches are shown in colour and indicated by base. (DOCX 3674 kb)