mrna mrnas cdna cdnas rna rnas exon exons 5 3 alternative altered alternate alternated alternately alternatively major long elongated predominant minor short rare same single variant variants isoforms isoform form forms splice spliced splicing process processed processing novel new additional distinct multiple differential differentially aberrant aberrantly generate generates generated transcript transcripts demonstrated demonstrate analysis analysed two three four five six seven eight nine first second polyadenylation polyadenylated junction junctions pattern patterns