disease and monitor for any possible long-term side effects of the gene therapy procedure. During the 
first year we would like to see you at monthly intervals after transplantation and during the second year 
every three months and then yearly unless there is a specific reason to see you more often. In the very 
unlikely event of your death we would like to request an autopsy for the purpose of determining 
whether the GC gene has been transferred into important organs such as marrow, liver and spleen. 
Your participation in this study will in no way alter the standard care you may be receiving. If you are 
currently receiving enzyme replacement therapy it will continue. Depending on how much of the GC 
enzyme is produced by your transplanted cells we may consider trying to reduce the amount of enzyme 
replacement therapy you are receiving. There will be no charge to you or your insurance carrier for 
any of the tests, procedures or hospital stays associated with this study. You will continue to be billed 
for the costs of standard care including enzyme replacement treatment. 
RISKS, STRESS, OR DISCOMFORT 
There are some potential risks to this procedure. Even though the virus used to insert the GC gene 
into your peripheral blood cells cannot grow and is considered harmless to you, it is possible that events 
could occur within the cell that would allow the virus to grow. To minimize this possibility, the 
preparations of virus used to insert the GC gene into your peripheral blood cells will be tested for the 
presence of infectious virus before being used to genetically alter your blood cells. However, since this 
is a new procedure we do not know whether or not the marked cells could become abnormal after they 
have been injected. There is a very remote possibility that the virus that is placed into your blood cells 
could cause the development of cancer in your body. In our opinion this risk is extremely low. You 
will therefore be monitored for the presence of infectious virus which may be associated with the 
development of cancer. In a number of animal experiments we have been unable to demonstrate either 
infectious virus production or the development of cancer due to infectious virus during an observation 
time of up to four years after treatment. In addition, in over 50 patients who have so far received cells 
treated with this type of virus, no safety hazards were recognized. 
In preparation for collecting your white cells as described above you will be treated with a special 
medication which stimulates the bone marrow to release bone marrow making cells into your blood. 
This medication is called G-CSF. It can cause temporary bone pain which would then be treated with 
pain medication. No major side effects of G-CSF have been seen so far. The collection of your white 
cells requires you to have a plastic tube placed in one of your veins. This tube is inserted into your 
chest and is necessary to handle the large volume of blood from which the white blood cells will be 
separated. There is a small chance of bleeding or accidentally entering the chest cavity. If this happens 
a tube will need to be placed in your chest for several days. This risk is very small as your catheter will 
be placed by an experienced physician. Collecting white blood cells (leukopheresis) requires that you 
are connected to a machine which separates and collects your white cells while at the same time 
returning your red blood cells to you. This procedure is without any major side effects. One potential 
minor side effect is that your red and white blood cell counts could be slightly lower at the end of the 
procedure. Therefore your blood counts will be monitored each morning to minimize this event to 
happen. The leukapheresis procedure will be repeated on four consecutive days. 
At the time the blood cells are infused back into your blood stream you may experience fever, chills, 
difficulty breathing, and rarely a severe allergic reaction that can lead to death. You will be treated for 
such an allergic reaction if it should occur. 
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Recombinant DNA Research, Volume 18 
