Yuan Jun-Hui, Cheng Xiaoyang, Matsuura Eiji, Higuchi Yujiro, Ando Masahiro, Hashiguchi Akihiro, Yoshimura Akiko, Nakachi Ryo, Mine Jun, Taketani Takeshi, Maeda Kenichi, Kawakami Saori, Kira Ryutaro, Tanaka Shoko, Kanai Kazuaki, Dib-Hajj Fadia, Dib-Hajj Sulayman D, Waxman Stephen G, Takashima Hiroshi
Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA.
J Peripher Nerv Syst. 2023 Dec;28(4):597-607. doi: 10.1111/jns.12590. Epub 2023 Aug 18.
Voltage-gated sodium channel Nav1.7, encoded by the SCN9A gene, has been linked to diverse painful peripheral neuropathies, represented by the inherited erythromelalgia (EM) and paroxysmal extreme pain disorder (PEPD). The aim of this study was to determine the genetic etiology of patients experiencing neuropathic pain, and shed light on the underlying pathogenesis.
We enrolled eight patients presenting with early-onset painful peripheral neuropathies, consisting of six cases exhibiting EM/EM-like disorders and two cases clinically diagnosed with PEPD. We conducted a gene-panel sequencing targeting 18 genes associated with hereditary sensory and/or autonomic neuropathy. We introduced novel SCN9A mutation (F1624S) into a GFP-2A-Nav1.7rNS plasmid, and the constructs were then transiently transfected into HEK293 cells. We characterized both wild-type and F1624S Nav1.7 channels using an automated high-throughput patch-clamp system.
From two patients displaying EM-like/EM phenotypes, we identified two SCN9A mutations, I136V and P1308L. Among two patients diagnosed with PEPD, we found two additional mutations in SCN9A, F1624S (novel) and A1632E. Patch-clamp analysis of Nav1.7-F1624S revealed depolarizing shifts in both steady-state fast inactivation (17.4 mV, p < .001) and slow inactivation (5.5 mV, p < .001), but no effect on channel activation was observed.
Clinical features observed in our patients broaden the phenotypic spectrum of SCN9A-related pain disorders, and the electrophysiological analysis enriches the understanding of genotype-phenotype association caused by Nav1.7 gain-of-function mutations.
由SCN9A基因编码的电压门控钠通道Nav1.7与多种疼痛性周围神经病变有关，以遗传性红斑性肢痛症（EM）和发作性极端疼痛障碍（PEPD）为代表。本研究的目的是确定神经性疼痛患者的遗传病因，并阐明其潜在的发病机制。
我们招募了8例早发性疼痛性周围神经病变患者，其中6例表现为EM/类EM障碍，2例临床诊断为PEPD。我们对18个与遗传性感觉和/或自主神经病变相关的基因进行了基因panel测序。我们将新的SCN9A突变（F1624S）引入GFP-2A-Nav1.7rNS质粒，然后将构建体瞬时转染到HEK293细胞中。我们使用自动高通量膜片钳系统对野生型和F1624S Nav1.7通道进行了表征。
在两名表现出类EM/EM表型的患者中，我们鉴定出两个SCN9A突变，I136V和P1308L。在两名诊断为PEPD的患者中，我们在SCN9A中又发现了两个突变，F1624S（新突变）和A1632E。对Nav1.7-F1624S的膜片钳分析显示，稳态快速失活（17.4 mV，p <.001）和缓慢失活（5.5 mV，p <.001）均出现去极化偏移，但未观察到对通道激活的影响。
我们患者中观察到的临床特征拓宽了SCN9A相关疼痛障碍的表型谱，电生理分析丰富了对Nav1.7功能获得性突变引起的基因型-表型关联的理解。
