Background

Wiskott-Aldrich syndrome (WAS) is a rare X-linked primary immunodeficiency disorder (PID) characterized by microthrombocytopenia, bloody diarrhea, eczema, recurrent infections, and a high incidence of autoimmunity and malignancy.

Objective

To investigate the mechanism of thrombocytopenia and infections in four boys of consanguineous parents from Lebanon.

Methods

Patient gDNA was studied using Next Generation Sequencing and Sanger Sequencing. Protein expression was determined by immunoblotting, and mRNA expression by semi-quantitative RT-PCR. F-actin polymerization and cellular proliferation were assayed by flow cytometry.

Results

We identified a threonine to a methionine change at position 45 (T45M) of the WAS protein (WASp) that abolished protein expression and disturbed F-actin polymerization and T cell proliferation, but not B cell proliferation. In addition, the levels of the WAS-interacting protein (WIP) were significantly decreased in the patients.

Conclusion

The mutation identified severely destabilizes WASp and affects the downstream signaling events important for T cell function, but not B cell function. It was previously known that the stability of WASp depends on WIP. In this manuscript, we report that the stability of WIP also depends on WASp. Finally, it is important to suspect X-linked PIDs even in consanguineous families.

Clinical implications

The patients are above the optimal age for transplant in WAS, and it is difficult to identify one or more donors for four patients, therefore, they represent ideal candidates for gene therapy or interleukin-2 therapy.

中文翻译：

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Wiskott-Aldrich综合征，来自黎巴嫩一个近亲家庭的四个男性兄弟姐妹。

背景

Wiskott-Aldrich综合征（WAS）是一种罕见的X连锁原发性免疫缺陷疾病（PID），其特征是微血小板减少症，血性腹泻，湿疹，反复感染以及自身免疫和恶性肿瘤的高发。

目的

调查血小板减少症和感染机制的四个黎巴嫩血缘父母的男孩。

方法

使用下一代测序和桑格测序研究了患者gDNA。通过免疫印迹确定蛋白表达，并通过半定量RT-PCR确定mRNA表达。F-肌动蛋白聚合和细胞增殖通过流式细胞术进行测定。

结果

我们发现苏氨酸在WAS蛋白（WASp）的第45位（T45M）处的蛋氨酸发生了变化，该变化消除了蛋白表达并扰乱了F-肌动蛋白的聚合和T细胞增殖，但没有扰乱B细胞增殖。另外，患者中WAS相互作用蛋白（WIP）的水平显着降低。

结论

鉴定出的突变严重破坏了WASp的稳定性，并影响了对T细胞功能（而非B细胞功能）重要的下游信号传导事件。以前已知WASp的稳定性取决于WIP。在此手稿中，我们报告在制品的稳定性还取决于WASp。最后，即使在近亲家庭中也要怀疑X连锁PID。

临床意义

这些患者的年龄超过了WAS移植的最佳年龄，并且很难为四名患者确定一个或多个供体，因此，它们代表了基因治疗或白介素2治疗的理想候选人。