British Journal of Haematology

Knowledge of the spectrum of symptoms in patients with inherited afibrinogenaemia is limited by the rarity of this coagulation defect. We compared a large series of 55 afibrinogenaemic patients from Iran with 100 patients with severe factor VIII deficiency. In afibrinogenaemia there was a higher frequency of mucosal‐type bleeding symptoms but joint and muscle bleeding was less frequent and severe than in haemophilia. Umbilical cord bleeding was relatively frequent only in afibrinogenaemic patients. Two young patients developed spontaneous thrombotic episodes and three women had recurrent abortions. Overall, in afibrinogenaemia bleeding symptoms are qualitatively different and less severe than in haemophilia. Afibrinogenaemia can also be accompanied by thrombotic manifestations.

We experienced three cases and four successful deliveries with congenital afibrinogenaemia and propose the following guidelines for the prenatal and peripartum management: (i) genital bleeding usually begins at 5 weeks' gestation and spontaneous abortion always occurs at 6–8 weeks' gestation without fibrinogen infusion; (ii) the fibrinogen level must be at least 0·60 g/l and, if possible, higher than 1·0 g/l during the pregnancy; (iii) the necessary amounts of fibrinogen increase as the pregnancy progresses and the preterm labour occurs; (iv) the fibrinogen level under the continuous infusion of fibrinogen during labour must be at least 1·5 g/l and, if possible, higher than 2·0 g/l to prevent placental abruption; (v) the puerperium is usually uneventful with a reduced dose of fibrinogen infusion.

The transcription factor Nuclear Factor‐Erythroid 2 (NF‐E2) is overexpressed in the vast majority of patients with polycythaemia vera (PV). In murine models, NF‐E2 overexpression increases proliferation and promotes cellular viability in the absence of erythropoietin (EPO). EPO‐independent growth is a hallmark of PV. We therefore hypothesized that NF‐E2 overexpression contributes to erythrocytosis, the pathognomonic feature of PV. Consequently, we investigated the effect of NF‐E2 overexpression in healthy CD34⁺ cells. NF‐E2 overexpression led to a delay in erythroid maturation, manifested by a belated appearance of glycophorin A‐positive erythroid precursors. Maturation delay was similarly observed in primary PV patient erythroid cultures compared to healthy controls. Protracted maturation led to a significant increase in the accumulated number of erythroid cells both in PV cultures and in CD34⁺ cells overexpressing NF‐E2. Similarly, NF‐E2 overexpression altered erythroid colony formation, leading to an increase in erythroid burst‐forming unit formation. These data indicate that NF‐E2 overexpression delays the early phase of erythroid maturation, resulting in an expansion of erythroid progenitors, thereby increasing the number of erythrocytes derived from one CD34⁺ cell. These data propose a role for NF‐E2 in mediating the erythrocytosis of PV.

The molecular aetiology of polycythaemia vera (PV) remains unknown and the differential diagnosis between PV and secondary erythrocytosis (SE) can be challenging. Gene expression profiling can identify candidates involved in the pathophysiology of PV and generate a molecular signature to aid in diagnosis. We thus performed cDNA microarray analysis on 40 PV and 12 SE patients. Two independent data sets were obtained: using a two‐step training/validation design, a set of 64 genes (class predictors) was determined, which correctly discriminated PV from SE patients. Separately 253 genes were identified to be upregulated and 391 downregulated more than 1·5‐fold in PV compared with healthy controls (P < 0·01). Of the genes overexpressed in PV, 27 contained Sp1 sites: we therefore propose that altered activity of Sp1‐like transcription factors may contribute to the molecular aetiology of PV. One Sp1 target, the transcription factor NF‐E2 [nuclear factor (erythroid‐derived 2)], is overexpressed 2‐ to 40‐fold in PV patients. In PV bone marrow, NF‐E2 is overexpressed in megakaryocytes, erythroid and granulocytic precursors. It has been shown that overexpression of NF‐E2 leads to the development of erythropoietin‐independent erythroid colonies and that ectopic NF‐E2 expression can reprogram monocytic cells towards erythroid and megakaryocytic differentiation. Transcription factor concentration may thus control lineage commitment. We therefore propose that elevated concentrations of NF‐E2 in PV patients lead to an overproduction of erythroid and, in some patients, megakaryocytic cells/platelets. In this model, the level of NF‐E2 overexpression determines both the severity of erythrocytosis and the concurrent presence or absence of thrombocytosis.

Acute chest syndrome (ACS) is a life‐threatening complication of sickle cell disease (SCD). A retrospective study was performed to evaluate the role of endothelial nitric oxide synthase (eNOS) gene polymorphisms (E298D and T‐786C) in African–American SCD patients. The D298 allele showed no association; the C‐786 allele showed a statistically significant association (P = 0·0061) in female ACS cases. Multiple logistic regression analysis showed that relative risk of ACS was 8·695 (P = 0·0076, 95% confidence interval 1·761–42·920) for female carriers of C‐786. eNOS T‐786C is a gender‐specific genetic modifier that is associated with increased susceptibility to ACS in female SCD patients.

Summary. Paediatric studies have demonstrated that l‐arginine (l‐arg), the precursor to nitric oxide, is diminished in vaso‐occlusive crisis (VOC). This study aimed to determine whether l‐arginine levels are altered in adult VOC in the emergency department. Plasma l‐arg and nitric oxide metabolite (NOx) levels were obtained in adult VOC patients presenting to the emergency department. Fifty patients had significantly low plasma l‐arg (29·78 μmol/l ± 11·21, P < 0·05 vs steady‐state control = 41·16 μmol/l ± 5·04) and significantly low plasma NOx (12·33 μmol/l ± 10·28, P < 0·05 vs steady‐state control = 25·2 ± 2·6 µmol/l). Neither l‐arg nor NOx levels could predict VOC clinical course.

Summary.The phenotypic screening for genetic haemochromatosis (GH) relies upon the determination of transferrin saturation (TS). In large‐scale screening programs, the time of blood sampling can be uneasy to control. We studied the circadian variations of TS at 08·00 hours, 12·00 hours, 18·00 hours and 00·00 hours in 46 C282Y homozygous patients (GH) and 47 non‐GH patients (NH), to determine whether the time of blood sampling influenced the results of screening. In both groups, there were significant circadian variations in TS, with the highest values at 08·00 hours and the lowest at 00·00 hours. For any given time‐point, TS was significantly higher in the GH group when compared with the NH group (P < 0·0001). For both groups, there was a significant decrease in TS between 08·00 hours and 00·00 hours (P < 0·0001) but this decrease was not as significant in GH when compared with NH patients (interactionP < 0·0073). Receiver operating characteristics (ROC) curves generated for TS at 08·00 hours, 12·00 hours, 18·00 hours and 00·00 hours, presented the same efficiency of diagnosis of GH, with TS threshold varying between 64% at 08·00 hours and 36% at 00·00 hours. In conclusion, for screening studies of C282Y homozygosity, determination of transferrin saturation may be performed at any time during the day.

Summary. A definite diurnal variation in serum iron exists in normal subjects, in which the serum iron levels are highest in the morning or at noon, and then gradually fall throughout the day to reach their lowest values in the evening; the serum iron concentration rises again the following morning after sleep. The diurnal rhythm may be regulated by the activity of the reticulo‐hypothalamic system, which may be under the influence of neurogenic or hormonal factors. Contrary to other workers, there is a definite diurnal variation in the serum iron concentration in patients with idiopathic haemochromatosis.