evidence of disease correlations with coronary 
artery disease, inflammatory bowel disease, and 
insulin-dependent diabetes mellitus. Studies of dis- 
ease association (linkage disequilibrium), sib-pair 
analysis, and linkage analysis will be performed. 
Molecular Genetic Studies 
of Cystic Fibrosis 
Cystic fibrosis (CF) is the commonest frequent 
lethal autosomal-recessive disease in Caucasians. Al- 
though the commonest mutation causing CF, a dele- 
tion of phenylalanine- 5 08 (AF508), is present on 
76% of Caucasian CF chromosomes, a large number 
of other mutations account for the remaining de- 
fects. For purposes of genetic counseling, prenatal 
diagnosis, carrier detection, and population screen- 
ing, it is desirable to test DNA samples for as many 
different CF mutations as possible using efficient 
methods. Dr. Beaudet's laboratory has developed 
methods to test simultaneously for 22 different CF 
mutations, using robotics to perform most of the 
testing with allele-specific oligonucleotides in a 
combinatorial format. Analysis of 22 mutations de- 
tects 89.5% of CF carriers in a sample of more than 
400 North American Caucasian CF chromosomes. 
In addition, the ligase chain reaction (LCR) has 
been evaluated for feasibility of detecting any small 
mutation in a multiplex format. Using a competitive 
LCR method with two common oligonucleotides on 
one side of the mutation and four oligonucleotides 
(two for mutant and two for normal) on the oppo- 
site side, single-base mutations are detected rou- 
tinely in this simple process. 
Multiplex analysis of different mutations in the 
same reaction is also possible. Methods for simulta- 
neous analysis of many single-base mutations will 
have general applicability for prereproductive 
screening and for disease-related testing in the popu- 
lation. Multiplex reproductive testing for diseases 
such as CF, Tay- Sachs disease, and Gaucher's disease 
is feasible, as is testing in the foreseeable future for a 
predisposition to emphysema, atherosclerosis, he- 
mochromatosis, cancer risks, and other disorders. 
In collaboration with Dr. Allan Bradley, gene tar- 
geting has also been used to introduce mutations 
into the CF gene of mice. Germline transmission of 
CF mutations has been obtained, and the mutant 
mice should be valuable for comparison with mice 
recently described by others, for studies of patho- 
physiology and for evaluation of pharmacologic 
trials and gene therapy. 
The project to obtain CF mutant mice was 
supported by a grant from the Cystic Fibrosis 
Foundation. 
Gene Cloning for Spinocerebellar 
Ataxia, Prader-Willi Syndrome, 
and Angelman Syndrome 
A long-standing collaboration with Dr. Huda 
Zoghbi aimed at positional cloning for the spinocer- 
ebellar ataxia 1 gene continues. Highly polymor- 
phic DNA markers that show no recombination with 
the disease locus have been obtained, and most of 
the candidate region is available in yeast artificial 
chromosome (YAC) clones. Candidate genes are be- 
ing isolated from the region. 
In another collaborative eff^ort, the laboratory of 
Dr. David Ledbetter has isolated YAC clones for the 
majority of the candidate region for the Prader-Willi 
syndrome and Angelman syndrome genes, both of 
which lie within a 3- to 4-Mb region on human chro- 
mosome 15. These human mental retardation syn- 
dromes are of particular interest because there is 
strong evidence of genomic imprinting, with the 
Prader-Willi gene expressed only from the paternal 
chromosome and the Angelman gene expressed only 
from the maternal chromosome. Dr. Beaudet's labo- 
ratory is isolating candidate genes from the YAC 
clones with the intent to test for genomic imprint- 
ing, to search for mutations in Prader-Willi and An- 
gelman patients, and ultimately to identify the dis- 
ease genes. Four candidate cDNA clones isolated 
from this region are being analyzed. 
Dr. Beaudet is also Professor in the Institute 
for Molecular Genetics and the Departments of 
Pediatrics and Cell Biology at Baylor College of 
Medicine. 
Articles 
Beaudet, A.L. 1992. Genetic testing for cystic fi- 
brosis. Pediatr Clin North Am 39:213-228. 
Demarquoy, J., Herman, G.E., Lorenzo, I., Trentin, 
J , Beaudet, A.L., and O'Brien, W.E. 1992. Long 
term expression of human argininosuccinate syn- 
thetase in mice following bone marrow transplan- 
tation with retrovirus-transduced hematopoietic 
stem cells. Hum Gene Ther 3:3-10. 
Ng, I S.L., Pace, R , Richard, M.V., Kobayashi, K., 
Kerem, B., Tsui, L.-C, and Beaudet, A.L. 1991. 
Methods for analysis of multiple cystic fibrosis 
mutations. Hum Genet ^7 -.615-611 . 
Sanders, W.E., Wilson, R.W., Ballantyne, CM., and 
Beaudet, A.L. 1992. Molecular cloning and analy- 
sis of in vivo expression of murine P-selectin. 
Blood 80:795-800. 
Sligh, J.E., Jr., Hurwitz, M.Y., Zhu, CM., Anderson, 
GENETICS 153 
