FIGURE 3.

Analysis of library mutants at the 5′ splice site of SMN1 exon 7/intron 7. A, fitness index values for mutants at the last positions of exon 7. Mutations that caused a significant decrease in the fitness index value are highlighted in red. All other mutations are in blue. B, maximum entropy scores for the wild-type (WT) 5′ splice site and the mutations at position 54, which is the last exonic nucleotide. Greater maximum entropy score correlate with more efficient splice site usage. The slash in the sequences denotes the exon-intron junction.