> Subject: RE: cryptorchidism study at Cornell
>
> PERMISSION TO CROSSPOST
>
> Here is the article from Dr Meyer-Wallen
>
> In the laboratories at the Baker Institute for Animal Health, Cornell
> University, Dr. Vicki Meyers-Wallen focuses upon inherited disorders
> that affect canine reproduction. Our goal is to identify genes that
> have a negative impact upon reproduction, with the final goal of
> producing practical tests to identify those carrying harmful
> mutations. The long
term
> goals are to reduce, and eventually remove, such deleterious genes
> from purebred dog populations, thus improving the reproductive
> soundness of purebred dogs.
>
> We are asking for breeders and owners to participate in our study by
> allowing us to collect blood samples from their dogs and related dogs.
> Those interested can e-mail Dr. Meyers-Wallen at
> vnm1@cornell.edu<about:blank>. We are studying the DNA to find the
> gene mutations that cause cryptorchidism (undescended testicles).
> Since this is the most prevalent inherited
disorder
> of the canine reproductive system, it would be very helpful to have a
> test to detect carriers of these genes. Then breeders could plan
> matings in
which
> no cryptorchid offspring would be produced, while allowing the
> offspring
to
> receive other desirable genes that such carriers may have.
>
> To this end, we have recently initiated studies of canine
> cryptorchidism, which is the failure of one or both testes to descend into the scrotum.
> Unilaterally cryptorchid dogs have only one testis in the scrotum.
> Bilaterally cryptorchid dogs have no testes in the scrotum. The
undescended
> testes may lie within the inguinal area or within the abdomen. This is
> an inherited disorder, and is inherited as a recessive trait. In the
> dog,
both
> testes normally descend into the scrotum by 2 weeks after birth (even
though
> one can not really feel them there at the time), but should be
> detectable
in
> the scrotum by 6 weeks of age.
>
> Based on the few pedigree studies in dogs and experimental studies in
other
> animals, testis descent in the dog is thought to be controlled by at
> least
3
> genes, the identity of which are unknown. Recessive mutations in such
genes
> result in cryptorchidism. Delayed descent of the testes may be a
> similarly inherited trait, as there is evidence in mice that mutations
> in 1 or 2 of the genes controlling testis descent in that species can
> result in delayed testis descent. It has been shown in other animals,
> such as pigs and
goats,
> that the prevalence of cryptorchidism in herds can be reduced over
> time by selecting against this trait. That is, cryptorchid animals and
> male and female parents of cryptorchid animals were not used as breeding stock.
This
> approach has not been used extensively in purebred dogs. However, if
> both male and female carriers could be identified by a practical test,
> then matings of carriers could be more easily avoided.
>
> The recently published canine genome sequence allows us to study dog
> genes more effectively. Using this information, we and our
> collaborators
studying
> human and mouse cryptorchidism, have performed pilot studies in dogs.
> We have not yet found mutations causing cryptorchidism, but we need to
examine
> many more dogs, their related family members, and dogs of several breeds.
In
> further studies, we plan to include dogs from family lines that have
> this problem, as well as a few lines that do not. All participants are
> purebred dogs, but their identity and that of their owners is held in confidence.
> That is, the identity of dogs and owners will be not be revealed by
> the researchers at any time. Using DNA markers and linkage analysis
techniques,
> as we have in other projects, we plan to examine DNA for markers that
allow
> us to identify the chromosome location of genes responsible for
> cryptorchidism. Once the locations are identified, the DNA sequence of
those
> regions is examined more closely to find specific genes and their
mutations.
>
> An example of another project in our lab in which this type of
> analysis is being used is our studies of inherited hermaphroditism
> (Sry-negative XX
sex
> reversal, visit our website at
>
http://bakerinstitute.vet.cornell.edu/rese...meyers_wallen.h
> tml<about:blank>
>
> Our final goal in this project will be to produce practical tests to
easily
> identify male and female carriers of this trait. In the end, it would
> be very helpful to have a test to detect carriers of these genes so
> that the breeder could plan matings in which no cryptorchid dogs would
> be produced, and still have the benefit of other desirable genes that
> such carriers may have. We hope that our research will benefit
> purebred dogs by
facilitating
> the production of reproductively sound lines of all breeds.
> Cryptorchid
dogs
> with a single testis descended, while of lower fertility, can reproduce.
> However, like begets like. The use of affected dogs as breeding stock
> will eventually lead to increasing numbers of unilaterally and
> bilaterally cryptorchid dogs. The American Veterinary Medical
> Association states that
it
> is unethical for a veterinarian to surgically correct this condition
without
> also neutering the animal, to prevent treated cryptorchid dogs from
> being deceptively presented as reproductively normal. Although medical
treatments
> have been proposed for this condition in the dog, there is no evidence
that
> any are efficacious. Neither surgery nor medical treatment will alter
> the affected dog's genetic makeup. Thus, reproduction from affected
> dogs and treatment of affected dogs may not be in the long term best
> interest of
the
> breeder, or the breed. Breeding of animals with late descending testes
> is likely to produce more animals with this condition, and worse, dogs
> in
which
> the testes fail to descend at all. In the end, a test to detect
> carriers
of
> these genes should lead to fewer cryptorchid dogs and improve
> reproductive soundness in all breeds ..........
>
> PERMISSION TO CROSSPOST
>
> Here is the article from Dr Meyer-Wallen
>
> In the laboratories at the Baker Institute for Animal Health, Cornell
> University, Dr. Vicki Meyers-Wallen focuses upon inherited disorders
> that affect canine reproduction. Our goal is to identify genes that
> have a negative impact upon reproduction, with the final goal of
> producing practical tests to identify those carrying harmful
> mutations. The long
term
> goals are to reduce, and eventually remove, such deleterious genes
> from purebred dog populations, thus improving the reproductive
> soundness of purebred dogs.
>
> We are asking for breeders and owners to participate in our study by
> allowing us to collect blood samples from their dogs and related dogs.
> Those interested can e-mail Dr. Meyers-Wallen at
> vnm1@cornell.edu<about:blank>. We are studying the DNA to find the
> gene mutations that cause cryptorchidism (undescended testicles).
> Since this is the most prevalent inherited
disorder
> of the canine reproductive system, it would be very helpful to have a
> test to detect carriers of these genes. Then breeders could plan
> matings in
which
> no cryptorchid offspring would be produced, while allowing the
> offspring
to
> receive other desirable genes that such carriers may have.
>
> To this end, we have recently initiated studies of canine
> cryptorchidism, which is the failure of one or both testes to descend into the scrotum.
> Unilaterally cryptorchid dogs have only one testis in the scrotum.
> Bilaterally cryptorchid dogs have no testes in the scrotum. The
undescended
> testes may lie within the inguinal area or within the abdomen. This is
> an inherited disorder, and is inherited as a recessive trait. In the
> dog,
both
> testes normally descend into the scrotum by 2 weeks after birth (even
though
> one can not really feel them there at the time), but should be
> detectable
in
> the scrotum by 6 weeks of age.
>
> Based on the few pedigree studies in dogs and experimental studies in
other
> animals, testis descent in the dog is thought to be controlled by at
> least
3
> genes, the identity of which are unknown. Recessive mutations in such
genes
> result in cryptorchidism. Delayed descent of the testes may be a
> similarly inherited trait, as there is evidence in mice that mutations
> in 1 or 2 of the genes controlling testis descent in that species can
> result in delayed testis descent. It has been shown in other animals,
> such as pigs and
goats,
> that the prevalence of cryptorchidism in herds can be reduced over
> time by selecting against this trait. That is, cryptorchid animals and
> male and female parents of cryptorchid animals were not used as breeding stock.
This
> approach has not been used extensively in purebred dogs. However, if
> both male and female carriers could be identified by a practical test,
> then matings of carriers could be more easily avoided.
>
> The recently published canine genome sequence allows us to study dog
> genes more effectively. Using this information, we and our
> collaborators
studying
> human and mouse cryptorchidism, have performed pilot studies in dogs.
> We have not yet found mutations causing cryptorchidism, but we need to
examine
> many more dogs, their related family members, and dogs of several breeds.
In
> further studies, we plan to include dogs from family lines that have
> this problem, as well as a few lines that do not. All participants are
> purebred dogs, but their identity and that of their owners is held in confidence.
> That is, the identity of dogs and owners will be not be revealed by
> the researchers at any time. Using DNA markers and linkage analysis
techniques,
> as we have in other projects, we plan to examine DNA for markers that
allow
> us to identify the chromosome location of genes responsible for
> cryptorchidism. Once the locations are identified, the DNA sequence of
those
> regions is examined more closely to find specific genes and their
mutations.
>
> An example of another project in our lab in which this type of
> analysis is being used is our studies of inherited hermaphroditism
> (Sry-negative XX
sex
> reversal, visit our website at
>
http://bakerinstitute.vet.cornell.edu/rese...meyers_wallen.h
> tml<about:blank>
>
> Our final goal in this project will be to produce practical tests to
easily
> identify male and female carriers of this trait. In the end, it would
> be very helpful to have a test to detect carriers of these genes so
> that the breeder could plan matings in which no cryptorchid dogs would
> be produced, and still have the benefit of other desirable genes that
> such carriers may have. We hope that our research will benefit
> purebred dogs by
facilitating
> the production of reproductively sound lines of all breeds.
> Cryptorchid
dogs
> with a single testis descended, while of lower fertility, can reproduce.
> However, like begets like. The use of affected dogs as breeding stock
> will eventually lead to increasing numbers of unilaterally and
> bilaterally cryptorchid dogs. The American Veterinary Medical
> Association states that
it
> is unethical for a veterinarian to surgically correct this condition
without
> also neutering the animal, to prevent treated cryptorchid dogs from
> being deceptively presented as reproductively normal. Although medical
treatments
> have been proposed for this condition in the dog, there is no evidence
that
> any are efficacious. Neither surgery nor medical treatment will alter
> the affected dog's genetic makeup. Thus, reproduction from affected
> dogs and treatment of affected dogs may not be in the long term best
> interest of
the
> breeder, or the breed. Breeding of animals with late descending testes
> is likely to produce more animals with this condition, and worse, dogs
> in
which
> the testes fail to descend at all. In the end, a test to detect
> carriers
of
> these genes should lead to fewer cryptorchid dogs and improve
> reproductive soundness in all breeds ..........
