The Dangers of Selective Breeding in Horses: An Overview of Hyperkalemic Periodic Paralysis
Impressive the Quarter Horse was not just the first Champion of the AQHA World Championship Show, but the index case of an autosomal dominant genetic disorder called Hyperkalemic Periodic Paralysis (HYPP). HYPP is caused by a mutation in the gene that codes for the sodium channels which replaces the normal amino acid leucine with phenylalanine. As a result, the channels occasionally become “stuck” open, leading to an abnormally high concentration of potassium in the extracellular space. HYPP causes attacks that are characterized by muscle weakness, paralysis, and involuntary recumbency. The muscle fibers become unable to maintain a stable membrane potential, though not all muscles throughout the body may be affected by an attack. Treatments focus on lowering the intake of potassium, maintaining normal exercise, and diuretics to increase the excretion of ions in the urine. HYPP can also be seen in humans with many of the same symptoms and triggers. In Quarter Horses, HYPP is paired with desirable muscle structure and traits which means a disease that could be breed out is found in almost 4.4% of Quarter Horses.
BIOL 311, Anatomy and Physiology 1
Tammy Bovee
Womack 100
11 – 11:30 AM