The detection of a novel mutation by screening SCN4A gene in normokalemic periodic paralysis

Objective To detect a novel mutation in SCN4A gene related to normokalemic periodic paralysis (normoPP) in one Chinese family.Methods Genomic DNA of two patients and their relatives in this family was extracted from peripheral blood leukocytes and amplified by polymerase chain reaction (PCR). All 24 exons of SCN4A gene were screened with denaturing high performance liquid chromatography (DHPLC) technology,and then sequence analysis of those DHPLC chromatograms showing heteroduplex were compared with the unaffected controls.Results Routine laboratory tests were carried on within normal ranges with the exception of an elevated creatine kinase (1126 U/L,normal 200 U/L) during an attack of weakness to the proband. Electromyograms and electrocardiograms were normal. Muscle biopsy showed no changes by light microscopy. A novel mutation G2101A predicting the amino acid exchange Arg675Gln in the segment 4 of domain Ⅱ of SCN4A was detected in both patients.Conclusions This novel mutation Arg675Gln should exist in Chinese patients,and might lead to normoPP.