DNA TESTS
In brief.
Although it is very rare, and there are very few known carriers, Fucosidosis is a condition that is fatal and dogs die
young. If 2 carriers of this condition, are mated, knowingly or unknowingly( if dogs are not tested) then all pups will
be affected. Rare or not, to me its not worth taking the risk of using an untested dog, when the test is available to
all. I would point out though, that if a carrier dog or untested dog is put to a DNA tested clear dog, that pups from
that mating will not get Fucosidosis but could be carriers themselves and any progeny from that mating, would
definitely need to be tested prior to mating.
PRA( Progressive Retinal Atrophy) is a condition , where springers go blind from this. Its usually late onset, in mid
or later years but has been known to happen to younger dogs also. The DNA test is for one type of PRA.
PFK ( Phosphofructokinase Deficiency) is an enzyme storage disease which causes abnormalities in red blood cells
and muscle cells. It can be mild or life threatening.
In more detail
FUCOSIDOSIS
Canine Fucosidosis is a disease which is severe, progressive and ultimately FATAL.
It is characterised by deteriorating signs of the nervous system that progress over a period of several months,
sometimes from an early age. Signs include inco-ordination and ataxia (loss of control of movement), change in
temperament, loss of learned behaviour, loss of balance, apparent deafness, visual impairment and varying degrees
of depression. The inco-ordination and ataxia affects all four legs and is mostly evident when affected animals are
walking on slippery surfaces or attempt more complicated movements such as turning. In addition, affected dogs
lose weight and may suffer from swallowing difficulties and sometimes regurgitation of food.
The disease, which affects young adults, usually between 18 months and 4 years of age, is caused by the absence of
an enzyme called alpha-L-fucosidase. This enzyme is one of many required to break down complex compounds into
simple molecules that the body can use. When this enzyme is absent, the pathway is blocked and the more complex
compounds build up in the cells of the affected animal, accumulating in the lymph nodes, liver, pancreas, kidney,
lungs and bone marrow. However, it is the accumulation in the brain and peripheral nerves that is most important,
since it interferes with normal function, giving rise to the clinical signs described, eventually resulting in death.
Fucosidosis can affect all English Springer Spaniels, whether’ work or show’ and ‘carriers ‘ in both types have
been found in this country, so we need to be aware and try to prevent this condition, which is ultimately fatal
from spreading into breeding lines.
Although it is very rare, has been reported by ESS owners/breeders from all over the world.
If your dog is DNA tested or hereditary clear/ non carrier for Fucosidosis then it will never get this
disease or pass it on to it offspring.
If your dog is DNA tested as a carrier for Fucosidosis ,then it will never get this disease but could pass it
on to it offspring and therefore if it is to be bred from, it should only be ‘put’ to a ‘DNA Fucosidosis
tested or Hereditary Clear’ dog.
If your dog is DNA tested Affected for Fucosidosis then sadly the prognosis is not good for your dog and
it must not be bred from.
PHOSPHOFRUCTOKINASE (PFK) DEFICIENCY.
PFK deficiency is an enzyme storage disease which causes abnormalities in red blood cells and muscle cells. It
is essential to get a proper diagnosis, as PFK deficiency can sometimes be confused with autoimmune haemolytic
anaemia and other acquired diseases Phosphofructokinase is a major regulatory enzyme found in all cells of the
body, which catalyses the metabolism of sugar into energy to maintain normal cell function. It is inherited through
a single autosomal recessive trait.
PFK deficiency can present as anything from mild to life-threatening episodic illness. Clinical signs may be
particularly noticeable in field trial/active working dogs, where weakness, exercise intolerance, muscle cramps,
poor performance or even outright refusal to move, may be observed.
A hallmark sign of this disease is intermittent dark urine (the colour ranging from orange to dark coffee-brown),
and, in severe cases, pale gums (anaemia) or jaundice (yellow colouration of skin and gums), with fever and poor
appetite. Clinical signs commonly develop following strenuous exercise, prolonged barking, or extensive panting, all
of which are conditions that accelerate the destruction of red blood cells in affected dogs.
A tiny change (point mutation) in the M-type phosphofructokinase gene was identified by research groups at the
University of Pennsylvania, which has resulted in the availability of a genetic screening (DNA) test for PFK
deficiency. This test accurately determines whether a dog is affected, a carrier, or a normal dog.
As with Fucosidosis , then English Springer Spaniels who are DNA tested for either PFK Deficiency or
PR cord 1 , the same rules apply…
If your dog is DNA tested or hereditary clear/ non carrier for PFK or PRA cord 1 then it will never get
this disease or pass it on to it offspring.
If your dog is DNA tested as a carrier for PFK or PRA cord 1 ,then it will never get this disease but
could pass it on to it offspring and if it is to be bred from,It should only be ‘put’ to a ‘DNA tested or
Hereditary Clear’ PFK or PRA cord 1 dog.
If your dog is DNA tested Affected for PFK or PRA cord 1 then it should not be bred from
Progressive Retinal Atrophy (PRA). PRA is the collective term for a group of inherited eye diseases, of which there
are several different, breed-specific forms that are due to mutations in different genes. In most forms of PRA the
rod photoreceptors in the retina (which are responsible for vision in low light conditions) degenerate before the
cone photoreceptors (which work best in mid to high levels of light and have the ability to detect colour).
Hence poor night vision, or night blindness, is often the first indication that a dog has PRA.
All forms of PRA studied to date result in blindness, but at different ages from a few months to several years.
The cord1 mutation can lead to blindness. It is also possible that dogs that are genetically affected, but that retain
vision into later life, can produce offspring that develop clinical signs and go blind at an early age, which is why its
so important that dogs are DNA tested. .
The DNA test for PRA that has been made available is for one specific mutation in one specific gene (known as
the ‘PRA Cord 1 Mutation'
Statistics from the AHT show that between 20 - 30% of dogs tested are genetic carriers for the Cord 1
mutation, with approximately 3% being genetically affected. It should be noted that these figures were obtained
using dogs NOT collected specifically for PRA research and thus represent a random cross section of the breed.
Irrespective of whether a second form of PRA exists in the Breed, the prevalence of this mutation alone in the UK
population is very significant.