Confirming Genetic Abnormalities of Hypokalemic Periodic Paralysis Using Next-Generation Sequencing: A Case Report and Literature Review

Hypokalemic periodic paralysis (hypoPP) is a disorder characterized by episodic, short-lived, and hypo-reflexive skeletal muscle weakness. HypoPP is a rare disease caused by genetic mutations related to expression of sodium or calcium ion channels. Most mutations are associated with autosomal dominant inheritance, but some are found in patients with no relevant family history. A 28-year-old man who visited the emergency room for paralytic attack was assessed in this study. He exhibited motor weakness in four limbs. There was no previous medical history or family history. The initial electrocardiogram showed a flat T wave and QT prolongation. His blood test was delayed, and sudden hypotension and bradycardia were observed. The blood test showed severe hypokalemia. After correcting hypokalemia, his muscle paralysis recovered without any neurological deficits. The patient's thyroid function and long exercise test results were normal. However, because of the history of high carbohydrate diet and exercise, hypoPP was suspected. Hence, next-generation sequencing (NGS) was performed, and a mutation of Arg669His was noted in the SCN4A gene. Although hypoPP is a rare disease, it can be suspected in patients with hypokalemic paralysis, and iden tification of this condition is important for preventing further attacks and improving patient outcomes. Diagnosing hypoPP through targeted NGS is a cost-effective and useful method.