Burmese hypokalemia is a condition connected to a low potassium ions concetration level in the blood serum. Potassium is the most abundant cation in mammals and plays a crucial role in the function of nervous tissue and muscle (skeletal, cardiac and smooth) throughout the body. To maintain ideal body homeostasis, potassium excretion and dietary intake must be balanced. Abnormalities of potassium homeostasis can occur as a primary condition, or as a secondary disorder.
Burmese hypokalemia or Burmese hypokaelemic periodic polymyopathy (BHP) is a disease characterized by muscle weakness associated with intermittent hypokalemia. Signs of Burmese hypokalemia are classically episodic, but in some cats weakness is incessant. During an episode, cats can present with severe generalized muscle weakness, although more commonly weakness of the cervical muscles as evidenced by ventroflexion of the head and neck, head bobbing and dorsal protrusion od the scapulae. The gait becomes short and maximal recruitment of motor units gives rise to muscle tremor. Cats with more generalized weakness have a crouching gait, especially evident in the hind limbs.
The disease usually becomes evident when kittens are two to six months of age, although some cases have not been detected until 2 years of age. Clinical signs may be triggered by stress or exercise. In some patients, the condition improves spontaneously or with therapy over a period of time, with some cats eventually not requiring on-going medication. However, some cats with Burmese hypokalemia have life-time requirements for a potassium supplementation.
Burmese hypokalemia (BHP) – genetics
BHP is caused by a missense mutation in WNK4 gene. The condition is inherited in a recessive autosomal way. The frequency of the affected allele in the breeding population is 14,9%. Genetic test for Burmese hypokalemia can assist breeders to avoid mating that could generate affected cats and identify carrier cats that could be excluded from the breeding program.
Gandolfi, B., Gruffydd-Jones, T.J., Malik, R., Cortes, A., Jones, B.R., Helps, C.R., Prinzenberg, E.M., Erhardt, G., and Lyons, L.A. (2012). First WNK4-Hypokalemia Animal Model Identified by Genome-Wide Association in Burmese Cats. PLoS One 7.
Malik, R., Musca, F.J., Gunew, M.N., Menrath, V.H., Simpson, C., Culvenor, J., Grahn, R.A., Helps, C., Lyons, L.A., and Gandolfi, B. (2015). Periodic hypokalaemic polymyopathy in Burmese and closely related cats: a review including the latest genetic data. J. Feline Med. Surg. 17, 417–426.