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MBTCA HEALTH
COMMITTEE REPORT OF JANUARY 5, 2001
This report will attempt to give
you an update on the two research projects currently being supported by the
MBTCA and the AKC Canine Health Foundation.
Dr. Eggleston's research :
University of California at Davis
I spoke to Erika Werne at the
AKC Health Foundation yesterday. I told her that, as far as I knew, our club
has not heard anything from Dr. Eggleston concerning sending cheek swabs or
whatever else she may need for her DNA studies. Erika presumes that Dr.
Eggleston is most likely starting with the material she already has from
Minis (the cheek swabs which Kevin Welch encouraged us to send to the
University of California at Davis two or three years ago) Erika expects a
progress report from Dr. Eggleston soon and will send a copy when it
arrives.
Dr. Johnson's research:
University of Missouri
Liz Hansen, the liaison person
for Dr. Johnson's lab, sent me an eight-page fax of the new proposal, which
Dr. Johnson has submitted to the AKC Canine Health Foundation. There are two
important differences in this new proposal: the title and the addition of
seven breeds besides the Miniature Bull Terrier.
First, the title.
"Molecular-Genetic Causes for Canine Lens Luxation and Glaucoma." There has
been considerable interest from other breeds, which also have lens luxation
problem. In at least some of these breeds, lens luxation is preceded by
glaucoma. In other, lens luxation seems to follow the onset of glaucoma.
There is apparently a connection between these two ophthalmic problems.
Since exactly what the connection is needs further study, Glaucomas has been
added to the project title. This seems like good news. There are presently
quite a few Minis being treated for high eye pressure (glaucoma) in the hope
of preventing future lens luxation.
The Sealyham Terrier people are
very interested in participating in the research. They have already supplied
blood samples and pedigrees from a whole family of dogs with a lens luxation
problem. The Tibetan Terrier people have done likewise.
Other breeds, which will be
included in the new proposal, are Basset Hounds, Jack Russell Terriers,
Petit Basset Griffon Vendeens, Welsh Springer Spaniels and Welsh Terriers.
All of these have some sort of lens luxation and/or glaucoma problem.
The inclusion of additional
breeds is also of great importance to spread the cost of the new proposal,
which asks for funding of up to $35,000/year for two years"
The following is a quote from
the pre-proposal:
"Summary: Heritable lens
luxation, if not treated promptly, will induce secondary glaucoma. In
addition, heritable primary glaucoma can cause secondary lens luxation.
Since it is not always known whether lens luxation or glaucoma is the
primary disease, we believe it is rational to study both diseases together.
Primary lens luxation is thought to be an autosomal recessive trait in
several breeds of true terriers including Miniature Bull Terriers, Jack
Russell Terriers, and Sealyham Terriers), in Tibetan Terriers, and in Petit
Basset Griffon Vendeens. Glaucoma is thought to be the primary disease in
Welsh Terriers, Basset Hounds and Welsh Springer Spaniels. The identity of
the mutant genes responsible for primary lens luxations and primary canine
glaucoma's has not yet been determined. Our long-range goal is to identify
the mutant genes and devise DNA markers for the respective disease loci to
assist dog breeders in producing offspring that will remain clear of lens
luxation and glaucoma. This will be accomplished by obtaining DNA samples
from affected dogs and their close relative. We will then test for
co-segregation (genetic linkage) between the disease phenotypes and marker
alleles either for candidate genes or for strategically placed loci from the
canine genome linkage map."
Elsewhere in the proposal, Dr.
Johnson explains why he needs to work with additional breeds. "The
nucleotide sequences from affected Miniature Bull Terriers were identical to
those of normal Miniature Bull Terrier and normal dogs from other breeds...
We concluded that because of intensive in-breeding and/or a narrow base of
founders, many of the alleles segregating in most breeds were lost from
Miniature Bull Terriers..."
Some other items of interest in
this eight page proposal include the following:
Seventy-seven samples have been
received from Mini Bulls, eight of these from luxated dogs.
Genes are known for two of the
major proteins which make up the zonules (fibers which hold the lens in
place). These two genes will be studied as likely "candidate genes". Some
defect in these genes may cause the fibers to break.
Studies are already underway
with Basset Hounds to test them with markers for two of the three genes
known to be involved in glaucoma in humans.
Dr. Johnson's lab plans to
establish an Internet web site for canine glaucoma/lens luxation. They
already have a site for canine epilepsy.
www.canine-epilepsy.net Liz
Hansen will manage the site.
A veterinary ophthalmologist
from Sweden, Dr. Kristine Narfstrom, has joined the faculty at the
University of Missouri. She is interested in collaborating on the proposed
lens luxation/glaucoma project. This is certainly good news as the
researchers to date have been mostly or entirely biochemists and
geneticists.
In my phone conversation with
Liz Hansen, she described a new machine now in use in their lab, which she
called a "genotyping machine". Whereas the old equipment could screen twenty
DNA samples for potential markers in one day, the new machine can do ninety
samples in three hours.
We must keep reminding all Mini
Bull owners, MBTCA members and non-members alike, that they should continue
to send blood samples from ALL Mini's to Dr. Johnson's lab. Normal dogs
today could be luxated dogs in the future. Obviously, a sample should be
sent from any dog that luxates.
It was a lucky day for Miniature
Bull Terriers when Lisa Bowers-Byrd located the canine genetics research lab
at the University of Missouri. Because Dr. Johnson was willing to work on
the lens luxation problem in Mini Bulls and because our club was willing to
financially support his research, at least seven other breeds now stand to
benefit from the proposed expanded study. The genetic blueprint for the Mini
Bull is apparently unique in the close similarity of each dog's DNA.
Hopefully, DNA from one of the other breeds being studied will be different
enough to separate normal from luxated individuals. The project at Davis
should also help to solve this dilemma by adding more markers and expanding
the map of the canine genome.
Good luck to all the canine
health researchers in 2001!
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