Joubert syndrome (JS) is a recessively inherited congenital ataxia characterized by hypotonia, psychomotor delay, abnormal ocular movements, intellectual disability, and a peculiar cerebellar and brainstem malformation, the “molar tooth sign.” Over 40 causative genes have been reported, all encoding for proteins implicated in the structure or functioning of the primary cilium, a subcellular organelle widely present in embryonic and adult tissues. In this paper, we developed an in vitro neuronal differentiation model using patient-derived induced pluripotent stem cells (iPSCs), to evaluate possible neurodevelopmental defects in JS. To this end, iPSCs from four JS patients harboring mutations in distinct JS genes (AHI1, CPLANE1, TMEM67, and CC2D2A) were differentiated alongside healthy control cells to obtain mid-hindbrain precursors and cerebellar granule cells. Differentiation was monitored over 31 days through the detection of lineage-specific marker expression by qRT-PCR, immunofluorescence, and transcriptomics analysis. All JS patient-derived iPSCs, regardless of the mutant gene, showed a similar impairment to differentiate into mid-hindbrain and cerebellar granule cells when compared to healthy controls. In addition, analysis of primary cilium count and morphology showed notable ciliary defects in all differentiating JS patient-derived iPSCs compared to controls. These results confirm that patient-derived iPSCs are an accessible and relevant in vitro model to analyze cellular phenotypes connected to the presence of JS gene mutations in a neuronal context.

朱伯特综合征 (JS) 是一种隐性遗传的先天性共济失调，其特征是肌张力低下、精神运动迟缓、眼球运动异常、智力障碍以及特殊的小脑和脑干畸形（“磨牙征”）。已报道超过 40 个致病基因，所有这些基因都编码与初级纤毛的结构或功能有关的蛋白质，初级纤毛是一种广泛存在于胚胎和成体组织中的亚细胞细胞器。在本文中，我们使用患者来源的诱导多能干细胞 (iPSC) 开发了体外神经元分化模型，以评估 JS 可能的神经发育缺陷。为此，将来自四名 JS 患者的 iPSC 与健康对照细胞一起分化，这些 iPSC 携带不同 JS 基因（AHI1、CPLANE1、TMEM67和CC2D2A）突变，以获得中后脑前体细胞和小脑颗粒细胞。通过 qRT-PCR、免疫荧光和转录组分析检测谱系特异性标记物的表达，对分化进行了 31 天的监测。与健康对照相比，所有 JS 患者来源的 iPSC，无论突变基因如何，都显示出类似的分化为中后脑和小脑颗粒细胞的损伤。此外，对初级纤毛计数和形态的分析显示，与对照组相比，所有分化的 JS 患者来源的 iPSC 均存在显着的纤毛缺陷。这些结果证实，患者来源的 iPSC 是一种易于使用且相关的体外模型，可用于分析与神经元环境中 JS 基因突变存在相关的细胞表型。