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Long QT Syndrome

Congenital LQTS is the most common of many inherited channelopathies identified in people and can cause Sudden death

Affected Genes: KCNQ1

Inheritance: Autosomal Dominant

Variant(canFam6):
chr18:45214221: C>A

Breed: English Springer Spaniels

General Information: Long QT Syndrome is a hereditary cardiac disorder that appears in dogs at any age, causing abnormal heart rhythms (arrhythmias) that can lead to episodes of fainting, seizures, or sudden death, particularly during periods of stress or excitement. This condition results from a mutation in genes that regulate the heart's electrical activity, leading to prolonged repolarization after each heartbeat (prolonged QT interval). The severity of symptoms can vary, and while some dogs may be asymptomatic, others can experience life-threatening episodes. Management includes regular monitoring and medication to control heart rhythm, and in some cases, lifestyle modifications to reduce stress and excitement.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected

One Variant Detected: Dog Possibly Affected

No Variants Detected: No Effect

Gene / Testing Information: Genetic testing of the KCNQ1 gene can identify whether a dog is a carrier of Long QT Syndrome. This disease is inherited in an autosomal dominant manner, meaning that only one copy of the mutated gene is necessary for the dog to be affected. Carrier dogs may show symptoms and can pass the mutated gene to their offspring. Breeding decisions should be made carefully to avoid producing affected pups, and genetic testing is crucial for informed breeding practices. Dogs that are not carriers have no increased risk of having pups with the disease.

References:
Ware WA, Reina-Doreste Y, Stern JA, and Meurs KM. Sudden Death Associated with QT Interval Prolongation and KCNQ1 Gene Mutation in a Family of English Springer Spaniels. J Vet Intern Med. 2015 29(2): 561–568.