hereditarydeseasesinsbts

Hereditary Deseases in SBTs

L2 HGA

There is a new condition we have just found in Stafford's it's called L2 HGA and its in all Stafford's this site has a health and fitness thread and in the section called L2HGA Results only you will find a dog from South Africa has just failed his genetic test for this brain disease and has been classified as a carrier . This L2 is inherited the same way as HC. You have to register as a member but we don't bite and we don't have anyone from your country so give it a go, it's full of good debates it's called www.bullbreedsonline.com

Laureen Williams (UK)

"Once a DNA test is available for any recessive inherited canine condition (such as L-2-HGA or Hereditary Cataract in the Staffordshire Bull Terrier) it should be used for two purposes. Firstly and foremost it should be used to avoid breeding further affected animals. Secondly, it can be used to eliminate the disease mutation from the breeding population, over time.

To avoid breeding affected animals the following 3 combinations of animals must be avoided:
a) affected x affected,
b) affected x carrier and
c) carrier x carrier.
While avoiding the breeding of affected animals however, it is also very important to avoid restricting the gene pool any more than is absolutely necessary and to maintain as many desirable breed characteristics as possible. To this end the Animal Health Trust recommends breeding with carrier and affected dogs as well as clear dogs, if they exhibit desirable characteristics, and as long as they are bred to dogs that have TESTED CLEAR of the condition. These combinations of dogs will produce puppies that are carriers, so it is essential any puppies that may be used for breeding are also tested, but no affected puppies will be produced and good breed characteristics will be maintained. Using this strategy the disease mutation can be eliminated slowly, over time, without any additional affected dogs being bred. There is no disadvantage to the individual dog to be a carrier. Its health is unaffected in any way."

I hope that does the job!

Cathryn Mellersh (cathryn.mellersh@aht.org.uk)

L-2-HGA IN STAFFORDSHIRE BULL TERRIERS

Submitted for publication by Roger Pugh (UK)

L-2-HGA (L-2-hydroxyglutaric aciduria) in Staffordshire Bull Terriers is a neurometabolic disorder characterized by elevated levels of L-2-hydroxyglutaric acid in urine, plasma and cerebrospinal fluid.

L-2-HGA affects the central nervous system, with clinical signs usually apparent between 6 months and one year (although they can appear later). Symptoms include epileptic seizures, “wobbly” gait, tremors, muscle stiffness as a result of exercise or excitement and altered behaviour.

The mutation, or change to the structure of the gene, probably occurred spontaneously in a single dog but once in the population has been inherited from generations to generation like any other gene. The disorder shows an autosomal recessive mode of inheritance: two copies of the defective gene (one inherited from each parent) have to be present for a dog to be affected by the disease. Individuals with one copy of the defective gene and one copy of the normal gene – called carriers – show no symptoms but can pass the defective gene onto their offspring. When two apparently healthy carriers are crossed, 25% (on average) of the offspring will be affected by the disease, 25% will be clear and the remaining 50% will themselves be carriers.

The mutation responsible for the disease has recently been identified at the Animal Health Trust. Using the information from this research, we have developed a DNA test for the disease. This test not only diagnoses dogs affected with this disease but can also detect those dogs which are carriers, displaying no symptoms of the disease but able to produce affected pups. Carriers could not be detected by the tests previously available which involved either a blood or urine test detecting elevated levels of L-2-hydroxyglutarate or magnetic resonance imaging. Under most circumstances, there will be a much greater number of carriers than affected animals in a population. It is important to eliminate such carriers from a breeding population since they represent a hidden reservoir of the disease that can produce affected dogs at any time.

The test is available now and information on submitting samples is given below. Breeders will be sent results identifying their dog as belonging to one of three categories:

CLEAR:	The dog has 2 copies of the normal gene and will neither develop L-2-HGA, nor pass a copy of the L-2-HGA gene to any of its offspring.
CARRIER:	The dog has one copy of the normal gene and one copy of the mutant gene that causes L-2-HGA. It will not develop L-2-HGA but will pass on the L-2-HGA gene to 50% (on average) of its offspring.
AFFECTED:	The dog has two copies of the L-2-HGA mutation and is affected with L-2-HGA. It will develop L-2-HGA at some stage during its lifetime, assuming it lives to an appropriate age.

Carriers can still be bred to clear dogs. On average, 50% of such a litter will be clear and 50% carriers; there can be no affected pups produced from such a mating. Pups which will be used for breeding can themselves be DNA tested to determine whether they are clear or carriers.