Genome editing to correct mutant genes and restore normal gene function may be a viable strategy for treating genetic diseases, report researchers from Children's Hospital of Philadelphia, who demonstrated the concept in a mouse model of hemophilia B (Li H et al. Nature. doi:10.1038/nature10177 [published online ahead of print June 26, 2011]).
Hemophilia B is caused by deficiency of blood coagulation factor IX, encoded by the F9 gene. Most affected persons have circulating levels of factor IX that are below 1% of normal; restoration to about 5% activity converts severe hemophilia B to a mild form.
Hampton T. Targeting Hemophilia. JAMA. 2011;306(5):480. doi:10.1001/jama.2011.1089