cells about 2 fold. We plan to use a dose of bone marrow-making cells that is 
usually used to replace the whole bone marrow. This dose may not work because 
your own bone marrow will be in competition with the new marrow. We will explain 
in the next paragraph what we will do if this happens. If the transplant does 
result in improvement in your enzyme system by 2 fold, we will follow you for 
about two years to see if the new marrow is making a difference in your disease. 
If we can not increase the amount of enzyme in a patient's white blood 
cells, it is because their own bone marrow makes too many enzyme-deficient cells 
which overwhelm the good cells. In this event, we would use drugs to destroy the 
bone marrow and allow the new marrow to take over completely. If this is 
necessary, the risks are greater for the patient. Life-threatening complications 
can occur. These are discussed in more detail below. We will make the decision 
on whether or not it is necessary to use these drugs to destroy the bone marrow 
on the basis of the studies in the first two patients involved in this project. 
We will advise you of these results and our plans. If you are one of these first 
two patients, we will discuss the options again with you before proceeding 
further with the study. 
Tests that will be done to assess your progress include blood tests, bone 
X-rays, special scans called magnetic resonance imaging (MRI) to measure the size 
of your organs and evaluate your bone problems, and a bone marrow biopsy. The 
blood tests will be done every month. The X-rays, scans, and bone marrow biopsy 
will be repeated every six months. 
RISKS AND BENEFITS : 
1. There is a risk that the gene placed in your cells will interfere 
with an important gene or activate an unwanted gene. This latter 
event could cause cancer or other presently unforeseen problems. 
While theory and a few studies indicate that this risk will be 
small, experience to date is limited. 
3. The collection of the white cells from your blood (leukopheresis) 
requires that you have a large I.V. tube placed in a vein that goes 
into your chest. This is necessary to handle the large volume of 
blood from which the white blood cells are separated. There is a 
small chance of bleeding or accidentally entering the chest cavity. 
If this happens, a tube would need to be placed in your chest for 
several days. Careful placement of the catheter by an experienced 
person minimizes these risks which are quickly reversible should 
they occur. 
4. In preparation for collecting the white cells discussed above, you 
would be treated with a special drug which stimulates the bone 
marrow to release bone marrow-making cells into the blood. This 
drug is called G-CSF. It can cause temporary bone pain during its 
use over a 10-20 day period. No major side effects of G-CSF have 
been reported. 
2. Leukopheresis or collecting white blood cells requires connecting 
you to a machine which separates and collects white cells while at 
the same time returns red blood cells to you. There are no major 
side effects to this procedure. A potential complication is that 
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