Development of mini genes
The size of the protein coding sequence of the USH2A gene (>15,000 bases!) is …………. A DNA fragment of such a length does simply not fit into the currently used gene therapeutic vectors (harmless viruses used for packaging genetic material and delivering this at its destination).
In the ‘minigenes’ project, the USH2A gene is artificially made smaller by taking specific parts of the gene and sticking these together (= minigene). This makes it possible to insert these minigenes into the current vectors for use in genetic therapy.
Erwin van Wijk is researcher at the Radboudumc Nijmegen, the Netherlands, and studies the question whether the functionality of various artificial, short forms of the USH2a protein (coded by so-called “mini-genes”) is sufficient to inhibit or even stop the deterioration of the eyesight. This is tested in the USH2a zebrafish model, which has been developed for this purpose.
The exon-skipping study for USH2a has shown earlier that some variation in the length of the USH2a gene/protein is possible without affecting the functioning.