avian & livestock genetic test data sheet

Swine Malignant Hyperthermia (MH) detection by PCR + RFLP

Test code GS002 - Identification of Malignant Hyperthermia (RyR1 R615C mutation) in pigs, by PCR+RFLP

Malignant hyperthermia (MH) in swine is caused by calcium dysregulation in muscle that can lead to sudden death and/or PSE (pale, soft, and exudative) meat. This disease is a rare life-threatening disease that is usually triggered by exposure to certain drugs used for general anesthesia, such as the volatile anesthetic agents and succinylcholine (a neuromuscular blocking agent). In susceptible individuals, these drugs can induce a drastic and uncontrolled increase in oxidative metabolism in skeletal muscle, which surpasses the body's capacity to supply enough oxygen, remove carbon dioxide, and regulate body temperature. Susceptible individuals eventually develop circulatory collapse and death if they are not immediately treated.

Recently, a mutation in ryanodine receptor 1 (RyR1 R615C mutation) has been found to be associated with MH. Ryanodine receptor 1, also known as skeletal muscle calcium release channel, is a calcium channel that mediates the release of Ca²⁺ from the sarcoplasmic reticulum into the cytoplasm and thereby plays a key role in triggering muscle contraction following depolarization of T-tubules. The receptor can also mediate the release of Ca²⁺ from intracellular stores in neurons, and may thereby promote prolonged Ca²⁺ signaling in the brain. The normal functioning of this receptor is required for normal embryonic development of muscle fibers and skeletal muscle, normal heart morphogenesis, skin development, and ossification during embryogenesis.

In the last several decades, extensive inbreeding of pigs to achieve better growth rate and meat quality has resulted in pigs with this mutation. This abnormality enhances the opening of Ca²⁺ channels and inhibits their closing, due to an altered low-affinity Ca²⁺ binding site in the channel pore.

In pigs carrying this mutation, stress or sudden changes in their environment may induce death. If these animals experience acute stress just prior to slaughter, then large segments of the carcasses result in pale, soft, exudative (PSE) pork (Rempel, W.E. et al., 1995). The condition is sometimes referred to as porcine stress syndrome (PSS) and is a serious economic problem in the swine industry. Genetic screening of breeders is important to help remove this mutation from herds.

Utilities:

• Identify and differentiate this mutation in swine
• Help remove this mutation from herds
• Enable breeding of pigs with specific genotypic characteristics

References:
Rempel, W.E., Lu, M.Y., Mickelson, J.R. and Louis, C.F. (1995) The effect of skeletal muscle ryanodine receptor genotype on pig performance and carcass quality traits. Animal Sci. 6:249-257.

Specimen requirements: Buccal swab, or 0.2 ml whole blood in EDTA (purple top) tube, or 0.2 ml fresh, frozen or fixed tissue.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 3 business days

Methodology: PCR + restriction fragment length polymorphism

Normal range: Not detected