Gene Therapy for Adenosine Deaminase 
Deficiency 
The ability to transfect pluripotent stem cells is 
paramount to the success of gene therapy by bone 
marrow transplant, because stem cells have the po- 
tential for both differentiation into all hematopoi- 
etic lineages and self-renewal. Recent efforts have 
focused on transfection of the stem cell-containing 
population bearing the CD34 glycoprotein on the 
cell surface. Colonies from transfected CD34^ cells 
that were maintained in long-term culture for more 
than five weeks demonstrated 40-60% infection ef- 
ficiency of the adenosine deaminase (ADA) gene 
based on proviral integration. ADA enzyme expres- 
sion in transfected cells from ADA-deficient bone 
marrow approached levels seen in normal subjects. 
Current efforts are concentrated on the design, opti- 
mization, and approval of a clinical trial utilizing 
autologous stromal support for retroviral superna- 
tant infection of CD34^ bone marrow progenitor 
cells. Since the stem cell-containing population is 
also thought to be present in peripheral blood, stud- 
ies have commenced on the potential use of CD34^ 
cells selected from mononuclear cells obtained dur- 
ing stem cell pheresis for transfection and long-term 
expression of the transfected ADA gene. This project 
was supported by a grant from the National Insti- 
tutes of Health. 
Generation of Animal Models 
of Human Disease 
Attempts to construct an ADA-deficient mouse are 
in progress using embryonal stem cell technology. 
This approach will replace normal regions of the 
gene by recombination with a mutation vector. Such 
technology was previously used to create a uricase- 
deficient mouse. The availability of these mouse 
models will permit both the study of ADA- and 
hypoxanthine guanine phosphoribosyltransferase 
(HPRT) -related immune deficiency and Lesch- 
Nyhan syndrome. 
Dr. Caskey is also Professor at the Institute for 
Molecular Genetics and Professor of Medicine, 
Biochemistry, and Cell Biology at Baylor College 
of Medicine. 
Books and Chapters of Books 
Bjorklund, A., Caskey, C.T., Gage, F.H., Hefti, F., 
Huttner, W.B., Julien, J. -P., Koliatsos, V.E., 
McKay, R.D.G., Pittman, R.N., Price, D.L., Risau, 
W., and Thoenen, H. 1991. Group report: neuro- 
nal replacement and functional modification. In 
Neurodegenerative Disorders: Mechanisms and 
Prospects for Therapy (Price, D.L., Thoenen, H., 
and Aguayo, A.J., Eds.). Chichester, UK: Wiley, pp 
271-290. 
Caskey, C.T. 1991. Genetic disorders. In Human 
Gene Transfer (Cohen-Haguenauer, O., and 
Boiron, M., Eds.). London: John Libbey Eurotext, 
vol 219, pp 17-26. 
Caskey, C.T., Edwards, A.O., and Hammond, H.A. 
1991 . DNA: the history and future use in forensic 
analysis. Proceedings of the 1989 International 
Symposium on the Forensic Application of DNA 
Analysis, FBI Academy, Quantico, VA, pp 3-9. 
Caskey, C.T., and Hammond, H.A. 1992. Forensic 
use of short tandem repeats via PCR. In Advances 
in Forensic Haemogenetics. Berlin: Springer- 
Verlag, pp 18-25. 
Caskey, C.T., and Rossiter, B.J.F. 1992. Molecular 
genetics. In Reproductive Risks and Prenatal 
Diagnosis (Evans, M.I., Ed.). Norwalk, CT: Ap- 
pleton & Lange, pp 265-274. 
Chamberlain, J. S., Gibbs, R.A., Ranier, J.E., and Cas- 
key, C.T. 1991. Detection of gene deletions using 
multiplex polymerase chain reactions. In Meth- 
ods in Molecular Biology: Protocols in Human 
Molecular Genetics (Mathew, C, Ed.). Clifton, 
NJ: Humana, vol 9, pp 299-312. 
Cournoyer, D., and Caskey, C.T. 1991. Gene re- 
placement therapy: strategies and progress. In 
Neurodegenerative Disorders: Mechanisms and 
Prospects for Therapy (Price, D.L., Thoenen, H., 
and Aguayo, A.J., Eds.). Chichester, UK: Wiley, pp 
165-180. 
Gibbs, R.A., Nguyen, P.-N., and Caskey, C.T. 1991. 
Direct DNA sequencing of complementary DNA 
amplified by the polymerase chain reaction. In 
Methods in Molecular Biology: Protocols in Hu- 
man Molecular Genetics (Mathew, C, Ed.). Clif- 
ton, NJ: Humana, vol 9, pp 9-20. 
Grompe, M., Mitani, K., Lee, C.C., Jones, S.N., and 
Caskey, C.T. 1991. Gene therapy in man and 
mice: adenosine deaminase deficiency, ornithine 
transcarbamylase deficiency, and Duchenne mus- 
cular dystrophy. In Purine and Pyrimidine Me- 
tabolism in Man V7/(Harkness, R.A., Elion, G.B., 
and ZoUner, N., Eds.). New York: Plenum, pp 
51-56. 
Munir, M.I., Rossiter, BJ.F., and Caskey, C.T. 1992. 
Antisense RNA production in mammalian fibro- 
blasts and transgenic mice. In Antisense RNA and 
DNA (Murray, J.A.H., Ed.). New York: Wiley-Liss, 
pp 97-108. 
Rossiter, BJ.F., Edwards, A. , and Caskey, C.T. 1991 . 
HPRT mutation and the Lesch-Nyhan syndrome. 
In Molecular Genetic Approaches to Neuropsy- 
chiatric Disease (Brosius, J., and Fremeau, R.T., 
Eds.). San Diego, CA: Academic, pp 97-124. 
GENETICS 165 
