The frequency distribution of mutation-induced aberrant 3' splice sites (3'ss) 
in exons and introns is more complex than for 5' splice sites, largely owing to 
sequence constraints upstream of intron/exon boundaries. As a result, prediction 
of their localization remains a challenging task. Here, nucleotide sequences of 
previously reported 218 aberrant 3'ss activated by disease-causing mutations in 
131 human genes were compared with their authentic counterparts using currently 
available splice site prediction tools. Each tested algorithm distinguished 
authentic 3'ss from cryptic sites more effectively than from de novo sites. The 
best discrimination between aberrant and authentic 3'ss was achieved by the 
maximum entropy model. Almost one half of aberrant 3'ss was activated by 
AG-creating mutations and approximately 95% of the newly created AGs were 
selected in vivo. The overall nucleotide structure upstream of aberrant 3'ss was 
characterized by higher purine content than for authentic sites, particularly in 
position -3, that may be compensated by more stringent requirements for positive 
and negative nucleotide signatures centred around position -11. A newly 
developed online database of aberrant 3'ss will facilitate identification of 
splicing mutations in a gene or phenotype of interest and future optimization of 
splice site prediction tools.