CRISPR/Cas9 Gene Editing Technology Used to Reverse Inversions Causing Hemophilia A Defect in Patient-Specific Stem Cells; This Success Points Way to Possible Cure

For the first time, chromosomal defects responsible for hemophilia have been corrected in patient-specific induced pluripotent stem cells (iPSCs) using CRISPR/Cas9 nucleases for gene editing. The scientific report of this possibly life-saving advance is titled “Functional Correction of Large Factor VIII Gene Chromosomal Inversions in Hemophilia A Patient-Derived iPSCs Using CRISPR-Cas9.” It published online on July 23, 2015 in Cell Stem Cell. Sufferers of hemophilia live in a perpetual state of stress and anxiety: their joints wear down prematurely and they have bleeding episodes that feel as if they will never end. Their bodies lack the ability to make the clotting factor responsible for the coagulation of blood so any cut or bruise can turn into an emergency without immediate treatment. Hemophilia A occurs in approximately 1 in 5,000 male births and almost half of severe cases are caused by identified “chromosomal inversions.” In a chromosomal inversion, the order of a sequence of base pairs on the chromosome is reversed so that a gene containing the inversion is not expressed properly. In chromosomal inversions in hemophilia A, the sufferer cannot express the blood coagulation factor VIII (F8) gene, and therefore lacks the protein (factor VIII) that causes blood to clot in healthy people. A Korean team, led by Director of the Center for Genome Engineering Dr. Jin-Soo Kim, Institute for Basic Science (IBS), and Professor Dong-Wook Kim at Yonsei University, has experimented with hemophilia-A-patient-derived induced pluripotent stem cells (iPSCs) and hemophilia mice and found a way to correct the hemophilia-A-causioning inversions and repair the clotting factor deficiency that causes hemophilia A.
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