Comprehensive detection of AS events

Comprehensive detection of AS events was performed by using vast-tools (version 0.2.1)¹³. We first mapped the reads in the fastq files generated above onto the reference human genome (hg19) using the ‘align' module of vast-tools with default parameters. Next, the results were merged into a single file containing PSI of each AS event in each individual using the ‘combine' module of vast-tools. By using the quality scores in the combined file (Column 8), we first excluded AS events whose Score 1 (read coverage based on actual reads) and Score 2 (read coverage based on corrected reads) in Column 8 did not meet the minimum threshold (mapped reads ≥10, in principle) in>20% of the individuals. We next excluded AS events whose PSI was 0 or 100% in >90% of the individuals. After performing these procedures, there were a total of 102,469 AS events. According to the predefined types of AS in vast-tools¹³, these were classified into Alt EX, Alt SS and IRs.