Gun Bilgic D.Aydin Gumus A.Gerik Celebi H.B.Bilgic A.Unaltuna Erginel N.Cam F.S.2024-07-222024-07-22202009675868http://akademikarsiv.cbu.edu.tr:4000/handle/123456789/13906Periodic paralyses (PPs) are a group of rare disorders characterized by episodic, sudden-onset, flaccid paralysis of skeletal muscles usually resulting in complete recovery after the attacks. PPs are caused by abnormal, mostly potassium-sensitive excitability of the muscle tissue. Hypokalemic and hyperkalemic periodic paralysis (HypoKPP and HyperKPP) have been described according to their characteristic phenotypes and the serum potassium level during the attacks of weakness. The T704M mutation on the SCN4A gene is the most common mutation in HyperKPP. Different mutations of the SCN4A gene have also been reported in some cases of HypoKPP. In this study, a large Turkish family carrying the T704M mutation on the SCN4A gene with HypoKPP disease was examined. A similar history was noted in a total of 17 subjects in the pedigree. SCN4A gene of the patients was sequenced with Sanger sequencing. In this study, this mutation was associated with a HypoKKP diagnosis for the first time in the literature. The symptoms of hallucination and diplopia seen in patients had also never been indicated in the literature before. This report expands the phenotypic variability of the T704M mutation, further confirming the lack of genotype-phenotype correlation in SCN4A mutations. © 2020 Elsevier LtdEnglishAdultFemaleHumansHypokalemic Periodic ParalysisMaleMuscle, SkeletalMuscular DystrophiesMutationNAV1.4 Voltage-Gated Sodium ChannelPedigreePhenotypePotassiumsodium channel Nav1.4potassiumSCN4A protein, humansodium channel Nav1.4adultagedArticleclinical articleclinical featurefemalegene mutationgenetic analysisgenetic associationgenetic variabilitygenetic variationgenotype phenotype correlationhumanhypokalemic periodic paralysismalemiddle agedperiodic paralysispriority journalSanger sequencingSCN4A genevery elderlyyoung adultgeneticsmuscular dystrophymutationpedigreephenotypeskeletal muscleArticle10.1016/j.jocn.2020.04.061