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Paroxysmal Dyskinesia (PxD) – Soft Coated Wheaten Terrier
| Acronym: | PxD |
| Gene: | PIGN |
| Mutation: | c.398C>T |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
| Method: | Sanger sequencing |
Genetics and characteristics
Paroxysmal dyskinesia (PxD) is an inherited disorder that affects the Soft Coated Wheaten Terrier breed. The disorder is characterized by episodic involuntary movements in form of focal motor seizures. Other names of paroxysmal dyskinesia are atypical epilepsy or episodic dyskinesia. Paroxysmal dyskinesia has been diagnosed also in human patients, where unlike the canine form of the disorder, PxD is inherited autosomal dominant. Among dogs, except Soft Coated Wheaten Terrier, PxD has been reported in several breeds, such as Cavalier King Charles Spaniel, Labrador Retrievers, Bichon Frise, Border Terrier, Chinook, Doberman Pinscher, English Bulldog, and Scottish Terrier. The canine form of the disorder shows a recessive mode of inheritance.
In veterinary medicine, paroxysmal dyskinesia is used as a wide term for cases of abnormal, sudden, involuntary contraction of a group of skeletal muscles that appears episodically. PxD episodes can be distinguished from seizures by lack of autonomic signs, EEG, abnormalities, or changes in consciousness during episodes. Affected dogs during PxD episodes remain conscious and appear to be visual, and may even obey commands during the episodes. The duration of the attack can vary from a few minutes to a couple of hours, and can sometimes occur in clusters. It can appear as an uncontrollable trembling or increased muscle tone, or simply as a head tremor, while the dog remains abnormally quiet.
Paroxysmal dyskinesia in Soft Coated Wheaten Terrier (PxD) is caused by a mutation in the PIGN gene. The disorder is inherited in an autosomal recessive pattern. A dog can be clear, carrier, or affected. Carriers of the gene are heterozygous and do not develop the disease’s symptoms. When mating two carrier dogs, each future cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Kolicheski, A. L., Johnson, G. S., Mhlanga-Mutangadura, T., Taylor, J. F., Schnabel, R. D., Kinoshita, T., … O’Brien, D. P. (2017). A homozygous PIGNmissense mutation in Soft-Coated Wheaten Terriers with a canine paroxysmal dyskinesia. Neurogenetics, 18(1), 39–47. http://doi.org/10.1007/s10048-016-0502-4
Urkasemsin, G., Olby, N. J. (2014). Canine Paroxysmal Movement Disorders. Vet Clin Small Anim 44, 1091–1102 http://dx.doi.org/10.1016/j.cvsm.2014.07.006