Large repository of human mRNA splicing mutations in TCGA and ICGC tumor exomes and genomes, with every mutation validated by transcriptome analysis of tumor vs controls:

Shirley BC, Mucaki EJ and Rogan PK. Pan-cancer repository of validated natural and cryptic mRNA splicing mutations. F1000Research 2019, 7:1908      (https://f1000research.com/articles/7-1908/v2)