title: Normokalemic periodic paralysis is not a distinct disease.
abstract: BACKGROUND
  Recent molecular studies of the original cases of normokalemic periodic paralysis (normoKPP) have raised suspicions that these families actually had hyperkalemic periodic paralysis (hyperKPP) due to mutations in the skeletal muscle sodium channel gene SCN4A. However, there is still a debate about the existence of normoKPP.
  
  
  METHODS
  We screened 230 individuals with primary periodic paralysis for mutations in the SCN4A, CACNA1S, and KCNJ2 genes. All patients had either a hyperKPP or a hypoKPP phenotype, and none had a normoKPP phenotype.
  
  
  RESULTS
  In 4 hyperKPP patients from 2 families, molecular analyses revealed Arg675Gly and Arg675Gln mutations of SCN4A, which were previously reported to cause normoKPP. Each patient exhibited the characteristic clinical and laboratory features (including hyperkalemia during spontaneous attacks) of hyperKPP.
  
  
  CONCLUSIONS
  Our findings support the notion that normoKPP is not a distinct disease.
authors.affiliation: Department of Pediatrics, Konyang University Hospital, Daejun, Republic of Korea.
authors.forename: Young-Wha
authors.initials: YW
authors.lastname: Song
authors.forename: Sung-Jo
authors.initials: SJ
authors.lastname: Kim
authors.forename: Tae-Hwe
authors.initials: TH
authors.lastname: Heo
authors.forename: Man-Ho
authors.initials: MH
authors.lastname: Kim
authors.forename: June-Bum
authors.initials: JB
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D001120:Arginine / Q000235:genetics; D004252:DNA Mutational Analysis; D004562:Electrocardiography; D005192:Family Health; D005260:Female; D005998:Glycine / Q000235:genetics; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics*; D062553:NAV1.4 Voltage-Gated Sodium Channel / Q000235:genetics*; D010245:Paralyses, Familial Periodic / Q000175:diagnosis / Q000235:genetics*
chemical_list: D062553:NAV1.4 Voltage-Gated Sodium Channel; C106251:SCN4A protein, human; D001120:Arginine; D005998:Glycine