In epithelia, claudin proteins are important components of the tight junctions as they determine the permeability and specificity to ions of the paracellular pathway. Mutations in CLDN10 cause the rare autosomal recessive HELIX syndrome (Hypohidrosis, Electrolyte imbalance, Lacrimal gland dysfunction, Ichthyosis, and Xerostomia), in which patients display severe enamel wear. Here, we assess whether this enamel wear is caused by an innate fragility directly related to claudin-10 deficiency in addition to xerostomia. A third molar collected from a female HELIX patient was analyzed by a combination of microanatomical and physicochemical approaches (i.e., electron microscopy, elemental mapping, Raman microspectroscopy, and synchrotron-based X-ray fluorescence). The enamel morphology, formation time, organization, and microstructure appeared to be within the natural variability. However, we identified accentuated strontium variations within the HELIX enamel, with alternating enrichments and depletions following the direction of the periodical striae of Retzius. These markings were also present in dentin. These data suggest that the enamel wear associated with HELIX may not be related to a disruption of enamel microstructure but rather to xerostomia. However, the occurrence of events of strontium variations within dental tissues might indicate repeated episodes of worsening of the renal dysfunction that may require further investigations.

中文翻译：

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claudin-10 缺乏对釉质形成的影响：来自 HELIX 牙齿的教训

在上皮细胞中，密蛋白是紧密连接的重要组成部分，因为它们决定了细胞旁通路离子的渗透性和特异性。CLDN10突变导致罕见的常染色体隐性遗传 HELIX 综合征（少汗症、电解质失衡、泪腺功能障碍、鱼鳞病和口腔干燥症），患者会出现严重的牙釉质磨损。在这里，我们评估这种牙釉质磨损是否是由与 claudin-10 缺乏症以及口腔干燥症直接相关的先天脆弱性引起的。从一名女性 HELIX 患者身上收集的第三颗磨牙通过显微解剖学和物理化学方法（即电子显微镜、元素映射、拉曼显微光谱和基于同步加速器的 X 射线荧光）的组合进行分析。牙釉质形态、形成时间、组织和微观结构似乎在自然变化范围内。然而，我们在 HELIX 牙釉质中发现了加重的锶变化，按照 Retzius 的周期性条纹的方向交替富集和耗尽。这些标记也存在于牙本质中。这些数据表明，与 HELIX 相关的牙釉质磨损可能与牙釉质微观结构的破坏无关，而是与口干症有关。然而，牙齿组织中锶变化事件的发生可能表明肾功能不全恶化的反复发作可能需要进一步调查。