This experimental gene therapy procedure, called RNA trans-splicing, repairs a mutated section of the gene responsible for hemophilia A. The disease affects 1 out of every 5,000-10,000 males and is caused by a defect in the coagulation factor VIII gene.

The mutation renders the factor VIII gene non-functional, and people with the disorder suffer from recurrent, non-predictable, spontaneous bleeding into major joints and soft tissues.

In this study, mice with hemophilia A were injected with a pre-trans-splicing molecule (PTM). It's designed to produce RNA (ribonucleic acid) that binds and splices onto the existing faulty RNA in order to correct it. The corrected RNA then encodes for the normal factor VIII protein.

In mice who received the PTM, factor VIII levels rose from lower than 1 percent to a maximum of 20 percent of normal factor activity, the study says. Those levels corrected the bleeding tendency of the hemophilia A mice.

The researchers say if this method proves effective in humans, it could provide more permanent treatment for people with hemophilia A.

Conventional gene therapy methods haven't been effective in treating hemophilia A. Currently, the disorder is treated with injections of factor VIII protein in response to bleeding incidents.

The research was to be presented today at the American Society of Gene Therapy's annual meeting in Boston.

More information

To learn more about hemophilia A, click here.