A 28-year-old male from rural Maharashtra is brought to the operating room for emergency appendectomy. Fifteen minutes after induction with propofol and intubation with succinylcholine, the patient develops masseter muscle rigidity, followed by generalized muscle rigidity, tachycardia (HR 145/min), and a core temperature of 39.2°C. Which is the most common genetic mutation associated with this malignant hyperthermia crisis?