Paroxysmal Dyskinesia (PxD) – Soft Coated Wheaten Terrier
Paroxysmal dyskinesia (PxD) is an inherited disorder which 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.
Characteristics and symptoms
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. Duration of the attack can vary from 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 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.
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