Deferred 
C. Selection of patients 
Estimate the number of patients to be involved in the proposed study 
of gene therapy. Describe recruitment procedures and patient 
eligibility requirements, paying particular attention to whether 
these procedures and requirements are fair and equitable. 
1. How many patients do you plan to involve in the proposed study? 
A number of patients would be needed in order to demonstrate efficacy. 
Initially, we would anticipate few patients - i.e., maybe 1-3 in the first 
year. This would allow effects to be carefully studied before further patients 
are treated. The number of ADA-deficient patients is quite small (see below) 
so that large numbers of patients are never likely. 
2. How many eligible patients do you anticipate being able to 
Identify each year? 
The incidence of ADA deficiency is estimated at < 1/100,000 live births; 
therefore, with 3,500,000 births/yr in the U.S., one would expect < 35 
patients/year. Approximately 1/3 would have an HLA-matched sibling and would 
be candidates for matched BMT. 
3. What recruitment procedures do you plan to use? 
We are already in communciation with a number of pediatric immunologists 
who are well aware of our direction. When the protocol has been submitted and 
approved and we are ready to begin clinical trials, they would be contacted 
directly. The Immune Deficiency Foundation is a national parents organization 
which keeps families current on research findings. We are in close contact 
with them. It is likely that the media will keep the general public and 
medical community informed. 
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