A method of gene therapy has been developed that exploits a natural process to accurately and permanently correct disease-causing genetic mutations.

By artificially initiating a DNA repair process called homologous recombination, Matthew Porteus of the University of Texas Southwestern and colleagues have replaced a mutated version of a gene linked with severe combined immunodeficiency disease (SCID)—so-called “bubble boy” disease.

The gene encodes a portion of the interleukin-2 receptor (IL-2R) in human cells. The treatment restored both gene function and the production of the IL-2R protein.

“SCID is ideal for this sort of therapy because you only need to correct the defect in a small number of immune cells to fix the problem,” says Porteus. “This is called selective advantage; the healthy cells grow and divide preferentially over the mutant ones.”

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