正常血钾型周期性麻痹存在SCN4A基因V781I突变

目的研究两例散发正常血钾型周期性麻痹(normokalemicperiodicparalysis,normoKPP)患者的临床特点及其电压门控钠通道型α亚单位(α-subunittypeofvoltage-gatedsodiumchannel,SCN4A)基因的突变。方法应用变性高效液相色谱(denaturinghighperformanceliquidchromatography,DHPLC)技术及测序分析检测患者SCN4A基因第13、19、23、24(部分)外显子是否发生已知导致高钾型周期性麻痹(hyperKPP)的突变(T704M、A1156T、M1360V、I1495F、M1592V);随后应用DHPLC技术筛查SCN4A基因其余外显子,对出现异常洗脱峰者进行测序分析。结果两例患者的SCN4A基因发生点突变2418(G→A)并引起氨基酸序列改变V781I,且为SCN4A基因唯一错义突变。病例1的父亲也发生该突变,但未发病。结论中国人normoKPP患者存在V781I突变,该突变可能是导致normoKPP的突变之一。

The mutation V781I in SCN4A gene exists in Chinese patients with normokalemic periodic paralysis

Objective In this report are reviewed two unrelated patients with typical normokalemic periodic paralysis (normoKPP) features and the results of screenig the SCN4A gene for the disease related mutation. Methods Two sporadic cases with normoKPP were screened for previously known mutations in SCN4A gene (T704M, A1156T, M1360V, I1495F, M1592V) that lead to hyperKPP; denaturing high performance liquid chromatography (DHPLC) was used. Then the rest exons of SCN4A gene were screened by DHPLC, and sequence analysis was performed on those with DHPLC chromatogram variation when compared with unaffected control. Results Two cases and one patient's father were detected with V781I, which was proved to be a singular missense mutation in SCN4A gene. Conclusion The mutation V781I exists in Chinese patients with normoKPP and may be responsible for normoKPP.