Schematic Representation of Integration of the Lentiviral Vector Construct into the HMGA2 Locus. The viral vector inserted into intron III of the HMGA2 gene, creating a fusion gene (shown as a line above the rectangles) that includes the first three exons of HMGA2 (shown as numbered gray boxes) and viral vector elements (VE) containing a cryptic splice site and the polyadenylation site (gray rectangle). The fusion mRNA transcript lacks exons IV and V of HMGA2 and is therefore missing binding sites for let-7 microRNAs that normally control protein expression. The bent arrows indicate the transcriptional direction of the fusion gene and β-globin genes.