My son has also got a splice site mutation. And here is what I have found out from a specialist:
``The genetic information to make the dystrophin protein is in 79 separate
blocks. These blocks need to be joined to make a functional gene message,
and the boundaries of these blocks (exons) are defined by splice sites. If
one of these splice sites has a mutation, it is not recognized by the cell
machinery responsible for joining the blocks together, and the block gets
excluded. Depending on which block is affected, it may be possible to by
pass the problem using one of the antisense oligos (currently in trial is AVI-4658).
happens is that the cell splicing machinery looks for the next bit of
sequence that looks a bit like a splice site, and it uses that. These
splice site mutations often cause a few different splicing patterns, because
the cell can't find a 'perfect' splice site. Exons get left out and this
may have the same result as a frame shift deletion, or bits of intron are
retained with the exon.''
Do you know what his mutation is exactly? Phillip's is c.6615-1G>C in nomenclature that is recommended by Leiden Muscular Dystrophy website.