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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.

 

Vind asb aangeheg meer informasie oor die L2HGA en HC toetse asook die toets aanvraag vorm.  

Die prosedure werk soos volg:

Sodra die teler gereed is om die honde te laat toets, kan ek n koerier rel om die bloedmonster by die

 veearts te kom oplaai (koste is op die informasie dokument aangedui). Al wat ek nodig het is die veearts

 se fisiese adres, kontak nommer, n kontak persoon en die datum en beraamde tyd (oggend of middag)

 wanneer die monsters opgelaai moet word. Die aanvraag vorm (request form) moet asb vir elke hond wat

 getoets moet word ingevul word en die veearts wat die bloedmonster neem moet dit ook asb teken. Die

 vorm kan saam met die bloedmonster met die koerier gestuur word, of die teler kan dit faks of scan en e-

pos. Indien die teler die monsters hier wil kom aflaai of n ander koerier wil gebruik, is hulle ook meer as

 welkom.  

Sodra ons die monster ontvang het, begin ons met die analises en ons waarborg dat die resultate binne 10

werksdae gereed sal wees, maar gewoonlik is dit binne 3 5 dae gereed. Die resultate word direk na die

 teler per e-pos gestuur. 

Ek het die resultaat verslag wat ons vir Penny gegenereer het ook hier aangeheg as n voorbeeld van hoe

ons verslae lyk. Ons sit die werklike resultate wat ons vir die hond genereer ook in dat, indien die teler n

tweede opinie by enige genetikus wil kry, hulle dit kan doen. Indien jy wil h dat ek die grafiek in meer detail

vir jou moet verduidelik sal ek dit met graagte doen! 

Moet asb nie huiwer om my te kontak indien jy enige verdere informasie benodig nie! 

Groete, 

Henritte van der Zwan                                               

Animal Geneticist

Inqaba Biotechnical Industries (Pty) Ltd

Cell: 082 859 2229

Tel: 012 343 5829

Fax: 012 343 0287

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