"Jay Konduros used to rush home several times a year after accidentally cutting or bumping himself. There he would inject himself with refrigerated bloodclotting factor to prevent internal bleeding and extensive bruising and swelling. I was walking on eggshells all the time said the former aerospace engineer who has a blood disorder called hemophilia B. Then last year Konduros enrolled in a clinical trial receiving an experimental gene therapy at Childrens Hospital of Philadelphia. Almost immediately he began producing the missing clotting factor. Several weeks later after he dropped a heavy box on his shin he watched a bruise develop and shrink within hours. Are you kidding me he thought. Lifes easy if this is what happens. Konduros  who runs a bakery and cafe in southeastern Ontario is one of  men in an earlystage trial sponsored by Spark Therapeutics. https_story.htmlutm_term.dd The disorder is much more common in men than women. On Wednesday researchers reported that a single intravenous infusion of Sparks novel gene therapy enabled patients to safely produce sufficient clotting factor to prevent dangerous bleeding episodes. The treatment also nearly universally eliminated the need for preventive infusions of clotting factor a few times a week the scientists said. And its effects lasted after a year and a half the longest patient followup the therapy was continuing to work. The results published http Wednesday online in the New England Journal of Medicine represent another example of the genetherapy renaissance Matthew Porteus a pediatrician at Stanford University wrote in an accompanying editorial http He said the data suggests that the treatment ultimately might provide an ideal cure for hemophilia B. Still he noted the study has some limitations. The followup period was relatively short from  to  weeks in the new report longerterm studies are needed to prove safety and effectiveness over extended periods. In addition he said researchers need to find ways to provide the therapy to a broader group of people including children and to figure out how to reduce the costs involved. The researchers presented earlier findings httpir.sparktx.comnewsreleasesnewsreleasedetailssparktherapeuticsandpfizerpresentupdatedpreliminarydata on the gene therapy a year ago at the American Society of Hematologys annual meeting but the latest data covers a larger patient group and a longer time period. The hemophilia gene therapy is one of several being tested for conditions including sickle cell anemia and Huntingtons disease. The onetime treatments seek to fight the disease by adding correct copies of a patients defective genes. If approved such treatments are expected to command stratospheric prices. For example a separate Spark gene therapy for a rare type of childhood blindness which is on track for Food and Drug Administration clearance soon could cost  million per patient for infusions in both eyes according to some Wall Street analysts. Still the therapies can produce at least some offsetting savings. Porteus noted in his editorial that the hemophilia therapy resulted in savings of about  a year per patient because of the elimination of clottingfactor infusions. Other experts also were impressed by the results. The hemophilia study is small but very promising and it gives me the sense that gene therapy for hemophilia B is going to be at our disposal in no time maybe a few years from now said Aric Parnes who is associate director of the Boston Hemophilia Center at the DanaFarberBoston Childrens Cancer and Blood Disorders Center and wasnt involved in the study. One of the key things is how long will the treatment last Does it wane over time So far with a full year it doesnt look like that is happening. Lindsey George the lead investigator and a hematologist at Childrens Hospital of Philadelphia said that nine of the  men in the trial didnt experience any bleeding episodes after the gene therapy treatment. The one patient who needed clotting factor because of bleeding used  percent less than before she said. People were planning their lives around hemophilia and now they are doing activities that they werent before George said. One man who came in a wheelchair is now out of a wheelchair and is coaching Little League. People with hemophilia B inherit a gene mutation on the X chromosome that interferes with their ability to produce normal levels of bloodclotting factor IX. Because women have two copies of the X chromosomes the other one can compensate so they may carry the disease but not suffer from it. Bleeding episodes  which can result from injury or occur spontaneously  can cause extensive damage and be life threatening. The therapy developed by Spark a biotech company spun off from the Childrens Hospital of Philadelphia in  involves a bioengineered gene designed to prompt the body to produce increased levels of a different clotting factor. The gene is transported to the liver where clotting factor is made by a harmless virus called an adenoassociated viral vector. For the current trial which is being funded by Spark and Pfizer researchers used a clotting factor that is  to  times as strong as the normal version. The stronger factor is called Factor IXPadua because it was discovered in  in an Italian family. Patients produced clottingfactor levels that were enough to allow blood to clot but not to spur an undesirable immunesystem response the researchers said."