RT Journal Article SR Electronic T1 Nanopore sequencing of full-length BRCA1 mRNA transcripts reveals co-occurrence of known exon skipping events JF bioRxiv FD Cold Spring Harbor Laboratory SP 169755 DO 10.1101/169755 A1 Lucy C de Jong A1 Simone Cree A1 Vanessa Lattimore A1 George AR Wiggins A1 Amanda B. Spurdle A1 kConFab Investigators A1 Allison Miller A1 Martin A Kennedy A1 Logan C Walker YR 2017 UL http://biorxiv.org/content/early/2017/07/30/169755.abstract AB Laboratory assays evaluating the effect of DNA sequence variants on BRCA1 mRNA splicing may contribute to classification by providing molecular evidence. However, our knowledge of normal and aberrant BRCA1 splicing events to date has been limited to data derived from assays targeting partial transcript sequences. For the first time, we resolve the exon structure of whole BRCA1 transcripts using MinION nanopore sequencing of long-range PCR amplicons. Our study identified 32 BRCA1 isoforms, including 18 novel isoforms which comprised skipping of multiple contiguous and/or non-contiguous exons. Furthermore, we show that known BRCA1 exon skipping events, such as Δ(9,10) and Δ21, can co-occur in a single transcript, with some isoforms containing four or more alternative splice junctions. Our results highlight complexity in BRCA1 transcript structure that has not previously been described. This finding has key implications for predicting translation frame of splicing transcripts, important for interpreting the clinical significance of spliceogenic variants. Future research is warranted to quantitatively assess full length BRCA1 transcript levels, and to assess the application of nanopore sequencing for routine evaluation of potential spliceogenic variants.