Paroxysmal nocturnal hemoglobinuria (PNH) is a rare life-threatening disease resulting from clonal hematopoietic stem cell evolution. There is a strong link between PNH and other acquired bone marrow failure syndromes, including myelodysplastic syndrome (MDS). Cytogenetic, morphological abnormalities or both are observed in the range of MDS/PNH diagnosis. Herein, we investigate cytogenetic abnormalities in PNH patients. We found two patients with PNH clones and MDS-associated abnormalities that later disappeared. The first patient, originally diagnosed with MDS and Trisomy 6, developed a large PNH clone. At the time of PNH diagnosis, the abnormal cytogenetic clone was no longer detectable despite persistent trilineage dysplasia. In the second patient, a large PNH clone and MDS-defining abnormality were detected at diagnosis, without evidence of dysplasia. No cytogenetic abnormalities were evident after complement inhibition. Our report adds significant information on the complex link between MDS and PNH, suggesting that distinction between these entities may be difficult in some cases. Especially in transplant eligible patients, the clinical phenotype may be the leading feature for treatment decisions in the era of complement inhibition. Lastly, the transient presence of cytogenetic abnormalities is a unique characteristic of our patients’ course that needs to be further elucidated in larger studies.

阵发性夜间血红蛋白尿（PNH）是一种罕见的威胁生命的疾病，是由克隆性造血干细胞进化引起的。PNH与其他后天性骨髓衰竭综合症（包括骨髓增生异常综合症（MDS））之间有着密切的联系。在MDS / PNH诊断范围内观察到细胞遗传学，形态异常或两者兼有。本文中，我们调查了PNH患者的细胞遗传学异常。我们发现了两名患有PNH克隆和MDS相关异常的患者，这些患者后来消失了。第一例最初被诊断患有MDS和Trisomy 6的患者发展了一个大型PNH克隆。在进行PNH诊断时，尽管存在持续的三系发育异常，但仍无法检测到异常的细胞遗传克隆。在第二例患者中，在诊断时发现了较大的PNH克隆和MDS定义异常，没有发育异常的证据。补体抑制后没有明显的细胞遗传学异常。我们的报告增加了有关MDS和PNH之间复杂链接的重要信息，这表明在某些情况下可能很难区分这些实体。特别是在具有移植资格的患者中，临床表型可能是补体抑制时代治疗决策的主要特征。最后，细胞遗传学异常的短暂存在是我们患者病程的独特特征，在更大的研究中需要进一步阐明。特别是在具有移植资格的患者中，临床表型可能是补体抑制时代治疗决策的主要特征。最后，细胞遗传学异常的短暂存在是我们患者病程的独特特征，在更大的研究中需要进一步阐明。特别是在具有移植资格的患者中，临床表型可能是补体抑制时代治疗决策的主要特征。最后，细胞遗传学异常的短暂存在是我们患者病程的独特特征，在更大的研究中需要进一步阐明。