From: LARRY KLAES (ljk4@msn.com)
Date: Tue May 07 2002 - 14:41:07 PDT
----- Original Message -----
From: cunews@cornell.edu
Sent: Tuesday, May 07, 2002 5:27 PM
To: CUNEWS-LIFE_SCIENCE-L@cornell.edu; CUNEWS-VET-L@cornell.edu; CUNEWS-SCIENCE-L@cornell.edu
Subject: Cornell News: X-linked PRA
Discovery of gene defect in Siberian huskies and Samoyeds offers dog
'model' for studying inherited human blindness, researchers report
FOR RELEASE: May 7, 2002
Contact: Cydney Peters
Office: 607-256-5672
E-mail: chp4@cornell.edu
ITHACA, N.Y. -- Cornell University researchers say the discovery of
the two different mutations for X-linked progressive retinal atrophy
(XLPRA1 and XLPRA2) in dogs, as reported in the May 1, 2002, issue of
Human Molecular Genetics (Vol. 11, No. 9), provides a new animal
"model" for studying causes and testing treatments for inherited
human blindness.
Dogs' health and well-being will benefit, too, according to
scientists at the Baker Institute for Animal Health in Cornell's
College of Veterinary Medicine, because new gene-screening tests will
help detect disease-prone animals in breeding programs.
The journal report, "Different RPGR exon ORF15 Mutations in Canids
Provide Insights Into Photoreceptor Cell Degeneration," is the work
of Qi Zhang, Gregory M. Acland, Wen X. Wu, Jennifer L. Johnson, Sue
Pearce-Kelling and Gustavo D. Aguirre, all at Cornell; Brian Tulloch
and Alan F. Wright at the MRC Human Genetics Unit of Western General
Hospital in Edinburgh, Scotland; and Raf Vervoort at the University
of Leuven in Belgium.
Both XLPRA1 and XLPRA2 are part of the family of inherited retinal
degenerations in dogs, called progressive retinal atrophy (PRA). PRA
is the equivalent of retinitis pigmentosa (RP) in humans, and
X-linked RP is one of the major causes of human retinal blindness.
The potential for X-linked diseases is genetically transmitted, from
one generation to the next, by female organisms (which have two X
chromosomes, while males have one X and one Y chromosome). Animals
-- either human or canine -- with the potential for X-linked disease
are considered "normal" if they have none of the defective genes.
Females with one defective gene are "carriers" and can transmit
potential for the disease. "Affected" individuals have only the
disease gene and no normal gene.
The disease XLPRA1 is present, veterinary researchers say, in both
the Siberian husky and Samoyed breeds, and the mutations are the
same, suggesting that the mutation may have been present in a common
canine ancestor before the two breeds developed. Both the canine and
human inherited vision disorders involve the loss of photoreceptor
cells in the eye's retina responsible for black-and-white (rods) and
color (cones) vision. The genetic defect identified by Cornell
researchers in the recent study is a result of a complex mutation
pattern in the RPGR gene, which compromises the function and
viability of the photoreceptor cells. Since this mutation pattern in
the RPGR gene is the same in humans and dogs, the study provides new
information on the mechanism of disease that exists in human
patients, with RP3, the most prevalent form of X-linked retinitis
pigmentosa.
"This research holds promise for dogs and humans alike," says
Cornell's Aguirre. "Discoveries like this one show the value of the
canine model and of comparative genomic analysis to aid in our
understanding of gene function and disease, which are of importance
to humans and other species."
According to a recent report by the National Eye Institute, a primary
funder of the study, "the number of blind or visually impaired
Americans is likely to double over the next 30 years as the giant
baby boom generation ages." Many of these patients will suffer from
macular degeneration, the leading cause of blindness in the aging
population. Others, however, will suffer from RP, of which XLRP is
one of the most common forms of the disease. Funding for the Cornell
research team also was provided by the Foundation Fighting Blindness
and the Van Sloun Fund for Canine Genetic Research.
"This disease has very severe and devastating consequences in people
as in dogs," says Aguirre. "Having a model that so closely mimics
human retinal disease will allow us not only to study the mechanism
of the disease, but also explore gene therapy as a cure in both human
patients and dogs."
Related World Wide Web sites: The following sites provide
additional information on this news release. Some might not be part
of the Cornell University community, and Cornell has no control over
their content or availability.
o James Baker Institute: <http://bakerinstitute.vet.cornell.edu/>
o Optigen canine genetic testing service: <http://www.optigen.com/>
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The web version of this release may be found at
http://www.news.cornell.edu/releases/May02/XLPRA.chp.html
Cornell University News Service
Surge 3
Cornell University
Ithaca, NY 14853
607-255-4206
cunews@cornell.edu
http://www.news.cornell.edu
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