Objective Extra-axial cavernous hemangiomas (ECHs) are sporadic and rare intracranial occupational lesions that usually occur within the cavernous sinus. The aetiology of ECHs remains unknown. Methods Whole-exome sequencing was performed on ECH lesions from 12 patients (discovery cohort) and droplet digital polymerase-chain-reaction (ddPCR) was used to confirm the identified mutation in 46 additional cases (validation cohort). Laser capture microdissection (LCM) was carried out to capture and characterise subgroups of tissue cells. Mechanistic and functional investigations were carried out in human umbilical vein endothelial cells and a newly established mouse model. Results We detected somatic GJA4 mutation (c.121G>T, p.G41C) in 5/12 patients with ECH in the discovery cohort and confirmed the finding in the validation cohort (16/46). LCM followed by ddPCR revealed that the mutation was enriched in lesional endothelium. In vitro experiments in endothelial cells demonstrated that the GJA4 mutation activated SGK-1 signalling that in turn upregulated key genes involved in cell hyperproliferation and the loss of arterial specification. Compared with wild-type littermates, mice overexpressing the GJA4 mutation developed ECH-like pathological morphological characteristics (dilated venous lumen and elevated vascular density) in the retinal superficial vascular plexus at the postnatal 3 weeks, which were reversed by an SGK1 inhibitor, EMD638683. Conclusions We identified a somatic GJA4 mutation that presents in over one-third of ECH lesions and proposed that ECHs are vascular malformations due to GJA4 -induced activation of the SGK1 signalling pathway in brain endothelial cells. Data are available on reasonable request. Not applicable.

中文翻译：

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颅内轴外海绵状血管瘤的体细胞GJA4突变

目的 轴外海绵状血管瘤（ECH）是散发性且罕见的颅内职业性病变，通常发生在海绵窦内。ECH 的病因仍不清楚。方法 对 12 名患者（发现队列）的 ECH 病变进行全外显子组测序，并使用微滴数字聚合酶链反应 (ddPCR) 确认另外 46 例患者（验证队列）中已识别的突变。进行激光捕获显微切割（LCM）来捕获和表征组织细胞亚群。在人脐静脉内皮细胞和新建立的小鼠模型中进行了机制和功能研究。结果 我们在发现队列中 5/12 名 ECH 患者中检测到体细胞 GJA4 突变（c.121G>T，p.G41C），并在验证队列中证实了这一发现 (16/46)。LCM 随后进行 ddPCR 显示该突变在病变内皮细胞中富集。内皮细胞的体外实验表明，GJA4 突变激活了 SGK-1 信号传导，进而上调了参与细胞过度增殖和动脉规格丧失的关键基因。与野生型同窝小鼠相比，过表达 GJA4 突变的小鼠在出生后 3 周时视网膜浅表血管丛出现类似 ECH 的病理形态学特征（静脉腔扩张和血管密度升高），但 SGK1 抑制剂 EMD638683 可逆转这一特征。结论 我们发现超过三分之一的 ECH 病变中存在体细胞 GJA4 突变，并提出 ECH 是由于 GJA4 诱导脑内皮细胞中 SGK1 信号通路激活而导致的血管畸形。可根据合理要求提供数据。不适用。