We describe the clinical, hematologic and genetic characteristics of a retrospective series of 126 subjects from 64 families with hereditary xerocytosis. Twelve patients from six families carried a KCNN4 mutation, five had the recurrent p.Arg352His mutation and one had a new deletion at the exon 7-intron 7 junction. Forty-nine families carried a PIEZO1 mutation, which was a known recurrent mutation in only one-third of the cases and private sequence variation in others; 12 new probably pathogenic missense mutations were identified. The two dominant features leading to diagnosis were hemolysis that persisted after splenectomy and hyperferritinemia, with an inconstant correlation with liver iron content assessed by magnetic resonance imaging. PIEZO1 -hereditary xerocytosis was characterized by compensated hemolysis in most cases, perinatal edema of heterogeneous severity in more than 20% of families and a major risk of post-splenectomy thrombotic events, including a high frequency of portal thrombosis. In KCNN4 -related disease, the main symptoms were more severe anemia, hemolysis and iron overload, with no clear sign of red cell dehydration; therefore, this disorder would be better described as a ‘Gardos channelopathy’. These data on the largest series to date indicate that PIEZO1 -hereditary xerocytosis and Gardos channelopathy are not the same disease although they share hemolysis, a high rate of iron overload and inefficient splenectomy. They demonstrate the high variability in clinical expression as well as genetic bases of PIEZO1 -hereditary xerocytosis. These results will help to improve the diagnosis of hereditary xerocytosis and to provide recommendations on the clinical management in terms of splenectomy, iron overload and pregnancy follow-up.

Calibrated Automated Thrombography (CAT) has been widely used to assess in vitro thrombin generation as an informative intermediary phenotype of coagulation. Interlaboratory exercises have documented a worrisome poor reproducibility. There are some data on the normalisation with an appropriate external reference plasma (RP). This multicentre study of the French-speaking CAT Club aimed at providing further evidence for the usefulness of such a normalisation

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Background:  Essential thrombocythemia (ET) is considered as a rare cause of stroke, partially because of difficulties to identify it when platelet count is not greatly elevated. However, early detection of ET is important because, without adapted treatment, recurrent thromboses are frequent. Method:  We collected, retrospectively, data from 14 cases of stroke patients with ET. Clinical characteristics, ischaemic stroke, laboratory data (platelet and leucocyte count, haemoglobin, JAK2 V617F mutation, culture of haematopoietic progenitors) and treatment were reviewed. Every patient has been interviewed by phone to evaluate outcome. Results:  The population consisted of nine women and five men with ages ranging from 40 to 87 years. Most of the patients (12) had atherosclerotic risk factors and two presented a thrombus in the internal carotid. ET was diagnosed early after the onset of stroke except in two patients. The platelet count was under 600*109/L for five patients. Mutation JAK2 V617F was found for eight patients. Thirteen patients were treated with an association between antiplatelet and cytoreductive treatment and did not present further thrombosis. Median follow‐up is 2.8 years. Conclusion:  These cases emphasize the problems of diagnosing ET at the onset of the stroke. Complete blood count has to be carefully read and ET can be suspected even if platelet count is not greatly increased. Diagnosis must be confirmed by haematologist to initiate appropriate treatment.