The present invention refers to splice shifting oligonucleotides (SSOs), targeting the downstream 3' splice acceptor site relative to microexons, which are mis-spliced in various diseases, particularly in neurological diseases like autism spectrum disorders (ASD) and schizophrenia.
1. Splice shifting oligonucleotides (SSOs) specifically binding selected regions of the 3' splice acceptor site downstream of a microexon, for use in the treatment of diseases characterized by altered inclusion of the microexon. 2. SSO, according to claim 1, specifically binding the 3' splice acceptor site downstream of microexon 4 of CPEB4 gene, for use in the treatment of neurologic diseases characterized by altered inclusion of microexon 4 of CPEB4 gene. 3. SSO, according to any of the previous claims, specifically binding the 3' splice acceptor site downstream of microexon 4 of CPEB4 gene at a location between nucleotides -5 and +22 relative to the first nucleotide of exon 5, for use in the treatment of neurologic diseases characterized by altered inclusion of microexon 4 of CPEB4 gene. 4. SSO for use, according to any of the previous claims, wherein the SSO is selected from the group comprising: SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11 or SEQ ID NO: 12. 5. SSO for use, according to any of the previous claims, in the treatment of neuro developmental/neurological disorders such as autism spectrum disorders or schizophrenia. 6. Method for modulating the splicing of alternatively spliced microexons, which comprises targeting a SSO to the 3' splice acceptor site downstream of the mis-spliced microexon. 7. Method, according to claim 6, for modulating the splicing of the microexon 4 of CPEB4 gene, which comprises targeting a SSO to the 3' splice acceptor site downstream of microexon 4 of CPEB4 gene. 8. Method, according to any of the claims 6 or 7, for modulating the splicing of microexon 4 of CPEB4 gene, which comprises targeting a SSO to the 3' splice acceptor site downstream of the microexon 4 of CPEB4 gene, preferentially at a location between the nucleotides -5 and +22 relative to the first nucleotide of exon 5. 9. Method, according to any of the claims 6 to 8, for modulating the splicing of microexon 4 of CPEB4 gene, which comprises the use of at least one of the following SSOs targeting to the 3'splice acceptor site downstream of the microexon: SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11 or SEQ ID NO: 12. 10. Method for screening SSOs for treatment of neurologic diseases characterized by altered inclusion of microexon 4 of CPEB4 gene, which comprises assessing whether the SSO targets the 3' splice acceptor site downstream microexon 4 of CPEB4 gene, wherein if the SSO targets the 3' splice acceptor site downstream microexon 4 of CPEB4 gene, is an indication that the SSO can be used for the treatment of neurologic diseases characterized by altered inclusion of microexon 4 of CPEB4 gene. 11. Method for screening SSOs for treatment of neurologic diseases characterized by altered inclusion of microexon 4 of CPEB4 gene, according to claim 10, which comprises assessing whether the SSO targets the 3' splice acceptor site downstream c microexon 4 of CPEB4 gene at a location between the nucleotides -5 and +22 relative to the first nucleotide of exon 5, wherein if the SSO targets the 3' splice acceptor site downstream microexon 4 of CPEB4 gene at a location placed between the nucleotides -5 and +22 relative to the first nucleotide of exon 5, is an indication that the SSO can be used for the treatment of neurologic diseases characterized by altered inclusion of microexon 4 of CPEB4 gene. 12. SSO characterized by targeting the 3' splice acceptor site downstream microexon 4 of CPEB4 gene selected from the group comprising: SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11 or SEQ ID NO: 12. 13. Pharmaceutical composition comprising at least one SSO according to claim 12 and, optionally, pharmaceutically acceptable excipients or carriers. 14. Pharmaceutical composition according to claim 13 for use in the treatment of neurologic diseases characterized by altered inclusion of microexon 4 of CPEB4 gene. 15. Pharmaceutical composition according to claim 13 or 14 for use in the treatment of neurological/neurodevelopmental diseases such as autism spectrum disorders or schizophrenia.