myopathy, previously known as HMLR, or Hereditary Myopathy, is an
autosomal recessive mutation that causes insufficient muscle function
in the Labrador Retriever breed. This
is due to the centralization
of the nuclei in muscle fibers, caused by an missense insertion
in the PTPLA gene.
are born apparently normal; however, it quickly becomes evident
that there is problem. The puppy will often not gain weight adequately,
due to decreased muscle tone in the esophagus. Within 2 to 5 months,
the disease has usually progressed to display the full range of
symptoms, including a loss of muscle tone and control,
an awkward gait, and extreme exercise intolerance. This condition
is exacerbated in cold conditions. Unfortunately, there is no cure
for CNM, as the dog will never develop properly functioning muscle
tissue. The dog usually has a normal life span, however, he will
always be plagued with the symptoms of Centronuclear Myopathy.
Centronuclear myopathy is a recessive
disorder, meaning that the dog must have two copies of the defective
gene to suffer from the disease. Because CNM is a recessive disorder,
a labrador can also be a carrier of this disease, meaning it carries
one copy of the mutation, but does not display any symptoms. A carrier
dog can pass on this mutation to their offspring, and if they mate
with another carrier dog, can produce offspring affected by Centronuclear
Animal Genetics offers
DNA testing and detection of the gene mutation responsible for Centronuclear
Myopathy in Labrador Retrievers.
US per sample.
Collect sample using buccal swabs provided by
Animal Genetics. Ensure that the dog has not eaten within a few
hours of sample collection. Any food particles can inhibit the test.
Rub each of the swabs along the inside of the dog's mouth for 10-15
seconds, and allow the swabs to dry thoroughly. Label the provided
envelope with the dog's name, and place the swab inside it. Download
and complete a submission form for each sample and send along with
payment to Animal Genetics for testing.
Results are given using the following symbolic
The dog carries two copies of the mutant gene and is homozygous
for Centronuclear Myopathy. The dog is affected by Labrador
Centronuclear Myopathy, and will always pass on a copy of the
mutated gene to its offspring.
Both the normal and mutant copies of the gene detected. Dog
is a carrier for Centronuclear Myopathy, and can pass on a copy
of the defective gene to its offspring.
Dog tested negative for the Centronuclear Myopathy gene mutation,
and will not pass on the defective gene to its offspring.