We report the case of a male patient who had a history of early-onset protein-losing enteropathy, chronic diarrhea, and repeated thrombotic events since early childhood. He developed Budd-Chiari syndrome with consequent acute liver failure that required liver transplantation when he was 12 years old. The initial graft failed to function and he required retransplantation. Steroid-resistant rejection complicated the clinical course after the second transplant. Treatment with antithymocyte globulin stabilized graft function but abdominal symptoms and enteral protein loss persisted. The patient remained dependent on intravenous albumin and immunoglobulin. Extended work-up for thrombophilia was unremarkable. Flow cytometry analysis of the peripheral blood cells revealed an unexplained CD55 deficiency. By sequencing of CD55 and, later, exclusion of alternative rare diseases by whole-exome sequencing, we discovered a novel, likely pathogenic homozygous splice-site variant in CD55 c.578 + 5G>A, NM_000574.4, OMIM 125240. The staining of liver and colon biopsies revealed a lack of CD55 protein expression. After initiation of treatment with eculizumab, the patient achieved and has maintained a complete clinical remission throughout 56 months of follow-up. We recommend testing for CD55 deficiency in patients with protein-losing enteropathy. In addition, CD55 deficiency should be considered in the differential diagnosis of patients with Budd-Chiari syndrome in whom an underlying cause is uncertain.

中文翻译：

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通过肝移植和依库丽单抗治疗 CD55 缺乏症布加氏综合征。

我们报道了一名男性患者的病例，该患者自幼年以来就有早发性蛋白质丢失性肠病、慢性腹泻和反复血栓事件的病史。12 岁时，他患上了布加氏综合征并导致急性肝功能衰竭，需要进行肝移植。最初的移植物未能发挥作用，他需要再次移植。类固醇抵抗性排斥反应使第二次移植后的临床过程变得复杂。抗胸腺细胞球蛋白治疗稳定了移植物功能，但腹部症状和肠内蛋白丢失持续存在。患者仍然依赖静脉注射白蛋白和免疫球蛋白。血栓形成倾向的延长检查未见异常。外周血细胞的流式细胞术分析显示存在无法解释的 CD55 缺陷。通过对 CD55 进行测序，并随后通过全外显子组测序排除其他罕见疾病，我们在 CD55 c.578 + 5G>A、NM_000574.4、OMIM 125240 中发现了一种新的、可能致病的纯合剪接位点变异。肝脏和结肠活检显示缺乏 CD55 蛋白表达。开始依库丽单抗治疗后，患者在 56 个月的随访中实现并保持了完全的临床缓解。我们建议对蛋白丢失性肠病患者进行 CD55 缺乏症检测。此外，在根本原因不确定的布加氏综合征患者的鉴别诊断中，应考虑 CD55 缺乏。