A difference in clinical manifestations of paroxysmal nocturnal hemoglobinuria (PNH) among different races has been suggested. The aim of this study was to clarify whether the clinical characteristics of patients with PNH in the International PNH Registry differ by ethnic background. Patients, who were eculizumab naïve at baseline and had ≥ 1% PNH clone size, were eligible for this analysis. Totally, 1793 patients were enrolled and divided into two cohorts, Asian (N = 246) and non-Asian (N = 1547). The Asian cohort was further divided into Asians in Asia cohort (N = 202) and Asians in non-Asia cohort (N = 44), based on geographical region. The Asian cohort had significantly higher PNH clone size in granulocytes, higher lactate dehydrogenase levels, and lower hemoglobin levels. However, the frequencies of symptoms including abdominal pain, backache, easy bleeding, fatigue and headache at baseline were significantly lower in the Asian cohort. The proportion of patients with a history of thromboembolism (TE) was significantly lower in the Asian than in the non-Asian cohort (3.6% vs. 8.9%, P < 0.01); however, there was no difference between Asians in Asia and Asians in non-Asia (3.3% vs. 4.9%, P = 0.61). These findings suggested that genetic factors may play a stronger role in developing TE than lifestyle factors in PNH patients.
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