A new clinical entity in T704M mutation in periodic paralysis

•Different SCN4A gene mutations cause different types of paralysis syndromes.•First family reported that inherits the T704M mutation with a HypoKPP clinic.•Unusual symptoms during the period of the attacks, diplopia and bad smelling in periodic paralysis patients.•We still need to improve genotype-p...

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Bibliographic Details
Published in:Journal of clinical neuroscience 2020-08, Vol.78, p.203-206
Main Authors: Gun Bilgic, Dilek, Aydin Gumus, Aydeniz, Gerik Celebi, Hamide Betul, Bilgic, Abdulkadir, Unaltuna Erginel, Nihan, Cam, Fethi Sirri
Format: Article
Language:English
Subjects:
Hypokalemic
Paralysis
Periodic
SCN4A
T704M
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Summary:•Different SCN4A gene mutations cause different types of paralysis syndromes.•First family reported that inherits the T704M mutation with a HypoKPP clinic.•Unusual symptoms during the period of the attacks, diplopia and bad smelling in periodic paralysis patients.•We still need to improve genotype-phenotype correlation in T704M mutation.•T704M mutation, showes interfamilial and intrafamilial clinical variability. Periodic 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.
ISSN:0967-5868
1532-2653
DOI:10.1016/j.jocn.2020.04.061