Abnormal insert-size principle applied to transcriptome data. The composite model of a gene is created via the union of the exonic nucleotides from all its isoforms. By using the composite model, we can exploit the abnormal insert-size principle. A minimal fusion transcript fragment is created by connecting the regions of the two genes joined by PE reads. Subsequently, the insert-size of these chimeric PE reads is computed and compared to the insert-size distribution of PE reads in the normal transcriptome. The higher insert-size compared to the transcriptome norm would suggest an artifact since it may be due to the random joining of fragments during library generation.