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Thromboembolic events and bleeding are known complications in essential thrombocythaemia (ET) and polycythaemia vera (PV). Using multiple Swedish health care registers, we assessed the rate of arterial and venous events, major bleeding, all-cause stroke and all-cause mortality in ET and PV compared to matched controls. For each patient with ET (n = 3141) and PV (n = 2604), five matched controls were randomly selected. In total, 327 and 405 arterial or venous events were seen in the group of ET and PV patients respectively. Compared to corresponding controls, the rate of venous thromboembolism, major bleeding and all-cause mortality per 100 treatment years was significantly increased among both ET (0.63, 0.79 and 3.70) and PV patients (0.94, 1.20 and 4.80). The PV patients also displayed a significantly higher rate of arterial events and all-cause stroke compared to controls. When dividing the cohort into age groups, we found a significantly higher rate of arterial and venous events in all age groups of PV patients, and the rate of all-cause mortality was significantly higher in both ET and PV patients in all ages above the age of 50. This study confirms that PV and ET are diseases truly marked by thromboembolic complications and bleeding.

Introduction: The management to reduce risk of thromboembolic complications in polycythemia vera and essential thrombocythemia are well established, but for other conditions with elevated hemoglobin, hematocrit, or platelets there are no consensus regarding treatment and follow up.

Aims: To assess frequency of elevated blood values in patients with thromboembolic event, how many of these should be investigated further regarding myeloproliferative neoplasm and if the risk of recurrent event is depending on underlying condition.

Methods: Retrospective cohort study of 3931 adult patients in the county of Norrbotten, Sweden, with thromboembolism during 2017 and 2018.

Results: Of the 3931 patients, 1195 had either elevated Hb, HCT, or platelets fulfilling the 2016 revised WHO criteria for PV and ET, and out of these 411 should be evaluated regarding underlying myeloproliferative neoplasms. Unexplained thrombocytosis and secondary erythrocytosis were associated with the highest rate of recurrent event as well as the most inferior restricted mean survival time.

Conclusion: Elevated blood values are common in patients with thromboembolic event and the high risk of recurrent event and inferior restricted mean survival time in patients with unexplained thrombocytosis and secondary erythrocytosis implicates the importance of finding and managing the underlying condition.

Background: Congenital dyserythropoietic anemia type III (CDA III) can be caused by mutation in KIF23. CDA III differs from CDA I and II in the sense that secondary hemochromatosis has not been reported. However, we have observed elevated serum ferritin in a CDA III family. Since primary hemochromatosis is common in Northern Europe we decided to screen the family for HFE mutations.

Aim: Study clinical appearance and prevalence of HFE gene mutations, C282Y and H63D, in a CDA III family. 

Methods: DNA from 37 CDA III patients and 21 non-affected siblings was genotyped. Iron status from EDTA plasma was measured in 32 of the CDA III patients and 18 of the non-affected siblings.

Results: Out of 37 CDA III patients, 18 carried heterozygous HFE mutations and six were compound heterozygotes. Out of 21 CDA III negative siblings, nine had heterozygous HFE mutations, two were homozygous (one H63D and one C282Y), and two were compound heterozygous. None of the patients with wt HFE, regardless of CDA III status, suffered from iron overload. Four patients with HFE mutations needed treatment with phlebotomy to normalize ferritin and transferrin iron saturation; one CDA III negative patient with homozygous C282Y, two CDA III patients with heterozygous HFE mutations and one CDA III case with compound heterozygosity.

Conclusion: HFE mutations were found in 65 % of CDA III patients and in 62 % of their CDA III negative siblings. Heterozygous HFE mutation, C282Y and even H63D, can cause iron overload when occurring concomitantly with CDA III.

The Congenital Dyserythropoietic Anemias (CDA) are rare hereditary hemolytic disorders with large bi- to multi-nucleated erythroblasts in the bone marrow. Hemolysis is negative in a direct antiglobulin test (DAT). Based on morphology and clinical picture, three major forms of CDAs, type I, II, and III have been defined. CDA III, dominantly inherited, constitutes the rarest type with a majority of cases belonging to a family in Västerbotten, Sweden. The genetic background of CDA I and CDA II has been linked to mutations in CDAN1 and SEC23B respectively. The mutation of CDA III has been linked to 15q22 in earlier studies.

In this project we have defined the causative genetic lesion in two families with CDA III. The novel mutation KIF23 c.2747C>G (p.P916R) was shown to segregate with CDA III in the Swedish and American CDA III families and was absent in 356 healthy controls. KIF23 encodes mitotic kinesin-like protein 1 (MKLP1), which plays a central role in the last step of cytokinesis. RNAi-based knock-down and rescue experiments demonstrated that the p.P916R mutation causes cytokinesis failure in HeLa cells, resulting in increasing number of bi-nuclear cells, consistent with appearance of large multinucleated erythroblasts in CDA III patients. We conclude that CDA III is caused by a mutation in KIF23, encoding MKLP1, a conserved mitotic kinesin crucial for cytokinesis.

Flow cytometry with eosin-5´-maleimide (EMA), anti-CD55 and anti-CD59 is commonly used when investigating non-autoimmune hemolytic anemias. Reduced fluorescence of EMA, typically detected in hereditary spherocytosis, is also seen in CDA II, while reduction of CD55 and CD59 characterizes paroxysmal nocturnal hemoglobinuria (PNH). We studied the flow cytometric profile of EMA, CD55, and CD59 on erythrocytes in CDA III. We found no abnormality of the erythrocyte membrane in CDA III and concluded that standard flow cytometry cannot be used to discriminate between CDA III and normal controls.

In CDA I and CDA II a majority of patients, including those who are not transfusion dependent, suffer from iron overload, which, according to earlier studies, is not the case in CDA III. We found that individuals of the Västerbotten CDA III family carry mutations in the hemochromatosis (HFE) gene. Three CDA III patients with heterozygous or compound HFE mutations need treatment with phlebotomy due to iron overload. One of them carries heterozygous H63D mutation, which is not reported to lead to iron overload by itself in otherwise healthy individuals. We propose that molecular genetic testing of the HFE gene is indicated in all patients with CDA, including CDA III.

Haplotype analysis and targeted next-generation resequencing allowed us to identify a mutation in the KIF23 gene and to show its association with an autosomal dominant form of congenital dyserythropoietic anemia type III (CDA III). The region at 15q23 where CDA III was mapped in a large Swedish family was targeted by array-based sequence capture in a female diagnosed with CDA III and her healthy sister. Prioritization of all detected sequence changes revealed 10 variants unique for the CDA III patient. Among those variants, a novel mutation c.2747C>G (p.P916R) was found in KIF23, which encodes mitotic kinesin-like protein 1 (MKLP1). This variant segregates with CDA III in the Swedish and American families but was not found in 356 control individuals. RNA expression of the 2 known splice isoforms of KIF23 as well as a novel one lacking the exons 17 and 18 was detected in a broad range of human tissues. RNA interference-based knock-down and rescue experiments demonstrated that the p.P916R mutation causes cytokinesis failure in HeLa cells, consistent with appearance of large multinucleated erythroblasts in CDA III patients. We conclude that CDA III is caused by a mutation in KIF23/MKLP1, a conserved mitotic kinesin crucial for cytokinesis.

Introduction: Flow cytometry with eosin-5´-maleimide (EMA), anti-CD55 and anti-CD59 is commonly used when investigating non-autoimmune hemolytic anemias. Reduced fluorescence of EMA, typically detected in hereditary spherocytosis is also seen in congenital dyserythropoietic anemia type II (CDA II). Reduction of CD55 and CD59 characterizes paroxysmal nocturnal hemoglobinuria (PNH). We studied the flow cytometric profile of EMA, CD55 and CD59 on erythrocytes in congenital dyserythropoietic anemia type III (CDA III). 

Methods: Erythrocytes from 16 CDA III positive individuals, 14 CDA III negative relatives and three normal controls per assay were studied with flow cytometry after EMA staining. Flow cytometry after anti-CD55 and anti- CD59 was performed on erythrocytes from 12 CDA III positive and 7 CDA III negative relatives with one normal control per assay. 

Results: CDA III - erythrocytes exhibited marginally stronger fluorescence after EMA-staining than normal controls. Correlation between EMA fluorescence and erythrocyte volume was confirmed. CDA III subjects did not differ from normal controls concerning CD55 and CD59. 

Conclusion: The results of the present study indicate no abnormality of the erythrocyte membrane in CDA III and show that standard flow cytometry cannot be used to discriminate between CDA III and normal controls. 

Between 1982 and 2009 a total of 92 patients with myelofibrosis (MF) in chronic phase underwent allo-SCT in nine Nordic transplant centers. Myeloablative conditioning (MAC) was given to 40 patients, and reduced intensity conditioning (RIC) was used in 52 patients. The mean age in the two groups at transplantation was 46±12 and 55±8 years, respectively (P<0.001). When adjustment for age differences was made, the survival of the patients treated with RIC was significantly better (P=0.003). Among the RIC patients, the survival was significantly (P=0.003) better for the patients with age <60 years (a 10-year survival close to 80%) than for the older patients. The type of stem cell donor did not significantly affect the survival. No significant difference was found in TRM at 100 days between the MAC- and the RIC-treated patients. The probability of survival at 5 years was 49% for the MAC-treated patients and 59% in the RIC group (P=0.125). Patients treated with RIC experienced significantly less aGVHD compared with patients treated with MAC (P<0.001). The OS at 5 years was 70, 59 and 41% for patients with Lille score 0, 1 and 2, respectively (P=0.038, when age adjustment was made). Twenty-one percent of the patients in the RIC group were given donor lymphocyte infusion because of incomplete donor chimerism, compared with none of the MAC-treated patients (P<0.002). Nine percent of the patients needed a second transplant because of graft failure, progressive disease or transformation to AML, with no significant difference between the groups. Our conclusions are (1) allo-SCT performed with RIC gives a better survival compared with MAC. (2) age over 60 years is strongly related to a worse outcome and (3) patients with higher Lille score had a shorter survival.