Mutations of sodium channel alpha-subunit genes in Chinese patients with normokalemic periodic paralysis.
OBJECTIVE
In this study, we aim to investigate the clinical features and Mutations of sodium channel alpha-subunit (SCN4A) genes in Chinese patients with normokalemic periodic paralysis (normoKPP).


METHODS
Six unrelated Chinese families with normoKPP were analyzed in clinical features. Genomic DNA was extracted from peripheral blood leukocytes and amplified with PCR. We screened all 24 exons of SCN4A gene with denaturing high performance liquid chromatography (DHPLC) technology, and then sequence analysis was performed in those who showed heteroduplex as compared with unaffected controls.


RESULTS
The laboratory tests were within normal ranges. Electromyograms and electrocardiograms were normal. One muscle biopsy was performed with the patient in family 4 after a brief attack of normoKPP. Examination of light microscopy showed no changes, but electronic microscopy showed occasionally degenerating myofibers. The mutations of SCN4A genes were as follows: (1) Met1592Val occurred in family 1. (2) Val-781-Ile occurred with the patient and her father in family 4. (3) Both the patients had a novel mutation g2101a predicting the amino acid exchange Arg675Gln in family 5, which may be a disease-causing mutation.


CONCLUSIONS
In addition to Val-781-Ile and Met1592Val, the mutation g2101a (Arg675Gln) may be the novel mutation of SCN4A genes in Chinese patients with normoKPP.
Department of Neurology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, China.
Guo
G
Xiuhai
Wu
W
Weiping
Zhu
Z
Ke
Wang
W
Hongbin
Si
S
Yiling
MaoYanling
D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D002681:China; D004252:DNA Mutational Analysis; D005260:Female; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D006801:Humans; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology*; D009154:Mutation / Q000235:genetics*; D062553:NAV1.4 Voltage-Gated Sodium Channel; D010245:Paralyses, Familial Periodic / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D015222:Sodium Channels / Q000235:genetics*
D005819:Genetic Markers; D062553:NAV1.4 Voltage-Gated Sodium Channel; C106251:SCN4A protein, human; D015222:Sodium Channels