The canonical intron splicing sites should be GT-AG, GC-AG and AT-AC, while other non-canonical splicing sites are mostly annotation errors.
However I still find some non-canonical splicing cases that have good transcriptome support. For example, the fourth intron in ENSMUST00000003725 in mouse (Could be found in Ensembl 65) is non-canonical (GT-CA, perhaps shift by 1 base when annotation), however in UCSC genome browser I find three mRNA sequences that support it (AB0112265, AK166423, BC021426).
How this intron was spliced out?
I appreciate your kind comment, but the url you gave was out of service now, would you like to send me straightly the title of your paper or the doi as the best ?
"A comprehensive survey of non-canonical splice sites in the human transcriptome" If you have any questions let me know.