Abstract:

Objective To screen the mutation sites of pathogenic genes of patients with primary hypokalemic periodic paralysis (HypoPP) and summary the clinical characteristics. Methods Medical histories of 35 patients with primary HypoPP were collected and relevant examinations were conducted. SCN4A, CACNA1S, KCNJ2, KCNJ5, and KCNE3 genes were detected by PCR and DNA sequencing. Two hundred healthy volunteers of the Han nationality were selected as controls. Results All patients had episodic myasthenia gravis. Serum potassium levels of 29 patients were low and serum potassium levels of 6 patients were normal during onset. Muscle weakness of all patients was alleviated after potassium supplement therapy. Two patients with familial HypoPP had mutations at c.2024G>A and c.2015G>A of SCN4A gene and both mutations had been reported. A patient with Andersen-Tawil syndrome had a novel mutation at c.919A>G of KCNJ2 gene, while this patients parents and 200 healthy controls did not have this mutation. Other 29 sporadic cases and 3 familial cases did not have mutations of SCN4A, CACNA1S, KCNJ2, KCNJ5, and KCNE3 genes. Conclusion HypoPP shows clinical and genetic heterogeneity. For patients with familial HypoPP, hot spot mutations of SCN4A gene should be screened first. For patients with periodic paralysis, dysplasia, and arrhythmia, KCNJ2 and KCNJ5 genes should be screened first.

Key words: hypokalemic periodic paralysis, Andersen-Tawil syndrome, mutation, SCN4A, KCNJ2