RYR1 (Ryanodine Receptor 1): RYR1 is a gene that encodes a calcium channel protein essential for muscle contraction. Genetic variations in RYR1 are associated with malignant hyperthermia, a rare but life-threatening reaction to certain anesthetics and muscle relaxants. Testing RYR1 can help identify individuals at risk, allowing for alternative anesthesia choices and safer surgical procedures.