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Charcot -Marie - Tooth (CMT ) / Demyelinating Polyneuropathy (DM / DPN / DMPN)
Test number: 8538
Gene: CMT
Price: £ 48.00 (including VAT)
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Breeds
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Lancashire Heeler
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Miniature Schnauzer
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The Disease |
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Charcot-Marie-Tooth type 4B2 is an inherited demyelinating peripheral nerve disease affecting the miniature schnauzer breed. Affected dogs show regurgitations caused by mega-esophagus and inspiratory dyspnea caused by laryngeal paralysis at a young age (< 2 years). Affected dogs have been alive more than 3 years following diagnosis which indicates a long survival rate. Typical pathological findings are variable thickness of the myelin sheath (so-called “tomacula”) around the axons of peripheral nerves and areas of segmental demyelination.
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Description |
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Charcot-Marie-Tooth Neuropathy (CMT)
Charcot-Marie-Tooth Neuropathy (CMT) is a hereditary neurological disorder caused by genetic mutations that affect peripheral nerve function.
It is characterised by progressive nerve damage, resulting in a range of symptoms that may include muscle weakness, neurological deficits,
and structural abnormalities. The disease's manifestation varies between breeds due to differences in the specific genetic variants responsible.
In affected breeds, CMT causes demyelination and pathological changes in the myelin sheath of nerve fibres, disrupting normal nerve signal transmission.
The condition is inherited in an autosomal recessive manner.
Comparison of CMT in Miniature Schnauzer and Lancashire Heeler
Miniature Schnauzer
- Gene: SBF2 (also known as MTMR13).
- Mutation: C-A.
- Symptoms: Affected dogs develop regurgitation due to megaesophagus and inspiratory dyspnoea caused by laryngeal paralysis.
Symptoms typically appear before 2 years of age.
- Pathology: Microscopic findings include variable thickness of the myelin sheath (referred to as “tomacula”)
and areas of segmental demyelination in peripheral nerves.
- Prognosis: Despite early onset, affected dogs can survive for more than 3 years post-diagnosis,
indicating a relatively long survival rate.
- Inheritance: Autosomal recessive.
- Breed Specificity: This variant has been identified only in Miniature Schnauzers.
Lancashire Heeler
- Gene: ITPR3.
- Symptoms: Dogs suffer from amelogenesis imperfecta, a severe developmental enamel defect characterised by yellow to brown tooth discolouration,
enamel hypoplasia, and abrasion leading to dentin exposure. The second primary symptom is subclinical peripheral neuropathy,
where dogs maintain normal locomotion and activity, but electrodiagnostic tests reveal neurogenic changes in distal muscles consistent with demyelinating neuropathy.
- Pathology: Significant enamel defects and mild demyelination-related neuropathies affecting distal limb muscles.
- Prognosis: Locomotion remains unaffected, with subclinical progression of neuropathy.
- Inheritance: Likely autosomal recessive.
- Breed Specificity: Associated with Lancashire Heelers.
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Trait of Inheritance |
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autosomal recessive trait
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Inheritance : AUTOSOMAL
RECESSIVE
trait
Sire
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Dam
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Offspring
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clear
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clear
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100% clear
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clear
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carrier
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50% clear + 50%
carriers
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clear
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affected
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100% carriers
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carrier
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clear
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50% clear + 50%
carriers
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carrier
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carrier
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25% clear + 25% affected
+ 50% carriers
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carrier
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affected
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50% carriers + 50%
affected
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affected
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clear
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100% carriers
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affected
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carrier
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50% carriers + 50%
affected
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affected
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affected
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100% affected
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Clear
Genotype: N / N [ Homozygous normal ]
The dog is noncarrier of the mutant gene.
It is very unlikely that the dog will develop Charcot -Marie - Tooth (CMT ) / Demyelinating Polyneuropathy (DM / DPN / DMPN). The dog will never pass the mutation to its offspring, and therefore it can be bred to any other dog.
Carrier
Genotype: N / CMT [ Heterozygous ]
The dog carries one copy of the mutant gene and one
copy of the normal gene.
It is very unlikely that the dog will develop Charcot -Marie - Tooth (CMT ) / Demyelinating Polyneuropathy (DM / DPN / DMPN) but since it carries the mutant gene, it can pass it on to its offspring with the probability of 50%. Carriers should only be bred to clear dogs. Avoid breeding carrier to carrier because 25% of their offspring is expected to be affected (see table above)
Affected
Genotype: CMT / CMT [ Homozygous mutant ]
The dog carries two copies of the mutant gene and
therefore it will pass the mutant gene to its entire offspring.
The dog is likely to develop Charcot -Marie - Tooth (CMT ) / Demyelinating Polyneuropathy (DM / DPN / DMPN) and will pass the mutant gene to its entire offspring
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Price
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£ 48.00 (including VAT)
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