背景:SCN5A编码的Nav1.5钠通道中的致病变异导致3型长QT综合征(LQT3)。这里,我们介绍了1例重度LQT3患儿,该患儿对多种药物治疗以及双侧星状神经节切除术均难以治疗.病人的新变种,p.F1760C-SCN5A,涉及Nav1.5局部麻醉结合域的关键残基。
目的:使用TSA-201和患者特异性诱导的多能干细胞衍生的心肌细胞(iPSC-CMs)对p.F1760C-SCN5A变体进行功能表征。
方法:使用全细胞膜片钳评估p.F1760C-SCN5A与利多卡因(Lido)相关的钠电流,氟卡尼(Flec),TSA-201细胞中的苯妥英(PHT)。产生p.F1760C-SCN5A和CRISPR-Cas9变体校正的等基因对照(IC)iPSC-CM。使用荧光电压染料测量有/没有美西律或PHT的动作电位持续时间(APD)。
结果:与野生型(WT)细胞(-86.3±0.9mV;p<0.0001)相比,在F1760C细胞(-72.2±0.7mV)中,失活的V1/2显著右移,导致窗口电流显著增加。F1760C将钠延迟电流从WT中的峰的0.18±0.04%增加2倍至F1760C中的峰的0.49±0.07%(p=0.0005)。F1760CiPSC-CM(601±4ms)与ICiPSC-CM(423±15ms;p<0.0001)相比,基线APD至90%复极化(APD90)显著增加。同时,用10μM美西律治疗4小时未能缩短APD90,用5μMPHT治疗可显着降低F1760CiPSC-CM的APD90(453±6ms;p<0.0001)。
结论:苯妥英拯救了一种新型p.F1760C-SCN5A变体的电生理表型和APD。抗癫痫药,苯妥英,可能是治疗LQT3的有效替代疗法,特别是对于破坏利多卡因/美西律结合位点的变体。
Pathogenic variants in the SCN5A-encoded Nav1.5 sodium channel cause type 3 long QT syndrome (LQT3). We present the case of an infant with severe LQT3 who was refractory to multiple pharmacologic therapies as well as bilateral stellate ganglionectomy. The patient\'s novel variant, p.F1760C-SCN5A, involves a critical residue of the Nav1.5\'s local anesthetic binding domain.
The purpose of this study was to characterize functionally the p.F1760C-SCN5A variant using TSA-201 and patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs).
Whole-cell patch clamp was used to assess p.F1760C-SCN5A associated sodium currents with/without lidocaine (Lido), flecainide, and phenytoin (PHT) in TSA-201 cells. p.F1760C-SCN5A and CRISPR-Cas9 variant-corrected isogenic control (IC) iPSC-CMs were generated. FluoVolt voltage dye was used to measure the action potential duration (APD) with/without
mexiletine or PHT.
V1/2 of inactivation was right-shifted significantly in F1760C cells (-72.2 ± 0.7 mV) compared to wild-type (WT) cells (-86.3 ± 0.9 mV; P <.0001) resulting in a marked increase in window current. F1760C increased sodium late current 2-fold from 0.18% ± 0.04% of peak in WT to 0.49% ± 0.07% of peak in F1760C (P = .0005). Baseline APD to 90% repolarization (APD90) was increased markedly in F1760C iPSC-CMs (601 ± 4 ms) compared to IC iPSC-CMs (423 ± 15 ms; P <.0001). However, 4-hour treatment with 10 μM
mexiletine failed to shorten APD90, and treatment with 5μM PHT significantly decreased APD90 of F1760C iPSC-CMs (453 ± 6 ms; P <.0001).
PHT rescued electrophysiological phenotype and APD of a novel p.F1760C-SCN5A variant. The antiepileptic drug PHT may be an effective alternative therapeutic for the treatment of LQT3, especially for variants that disrupt the Lido/
mexiletine binding site.