High levels of protein C are determined by PROCR haplotype 3.

BACKGROUND: Genetic determinants of plasma levels of protein C (PC) are poorly understood. Recently, we identified a locus on chromosome 20 determining high PC levels in a large Dutch pedigree with unexplained thrombophilia. Candidate genes in the LOD-1 support interval included FOXA2, THBD and PROCR. OBJECTIVES: To examine these candidate genes and their influence on plasma levels of PC. PATIENTS/METHODS: Exons, promoter and 3'UTR of the candidate genes were sequenced in 12 family members with normal to high PC levels. Four haplotypes of PROCR, two SNPs in the neighboring gene EDEM2 and critical SNPs encountered during resequencing were genotyped in the family and in a large group of healthy individuals (the Leiden Thrombophilia Study (LETS) controls). Soluble endothelial protein C receptor (sEPCR) and soluble thrombomodulin (sTM) plasma levels were measured in the family. RESULTS: PROCR haplotype 3 (H3) and FOXA2 rs1055080 were associated with PC levels in the family but only PROCR H3 was also associated with plasma levels in the healthy individuals. Carriers of both variants had higher PC levels than carriers of only PROCR H3 in the family but not in healthy individuals, suggesting that a second determinant is present. EDEM2 SNPs were associated with PC levels, but their effect was small. PC and sEPCR levels were associated in both studies. sTM was not associated with variations of THBD or PC levels. CONCLUSIONS: Chromosome 20 harbors genetic determinants of PC and sEPCR levels and the analysis of candidate genes suggests that the PROCR locus is responsible.

Use of the etonogestrel-releasing implant is associated with hypoactivation of the coagulation cascade.

BACKGROUND: The role of progestogens in haemostasis is controversial. Our objective is to evaluate the haemostatic effects of an etonogestrel-releasing implant. METHODS: This open-label, self-controlled, longitudinal study involved 20 healthy women receiving subcutaneous etonogestrel-releasing implants. At baseline, 1, 3 and 6 months, we measured the following: activated partial thromboplastin time; prothrombin time; thrombin time; fibrinogen; coagulation factors II, V, VII, VIII, IX, X and XI; von Willebrand factor; activated protein C (APC); antithrombin; free protein S; plasminogen activator inhibitor type 1 (PAI-1); alpha2-antiplasmin; thrombin-antithrombin (TAT) complex; prothrombin fragment 1 + 2 (F1 + 2); D-dimers; APC resistance. Statistical analyses included the Friedman test and ANOVA. RESULTS: Levels of APC (P < 0.01), factor II (P = 0.02), factor VII (P = 0.006), factor X (P = 0.01) and F1 + 2 (P < 0.001) were reduced, whereas those of PAI-1 (P = 0.01) and factor XI (P = 0.006) were transitory increased. All of these values, however, remained within normal ranges. Surprisingly, TAT concentrations fell below the normal range (P < 0.001). CONCLUSIONS: Our findings suggest that the etonogestrel-releasing implant does not induce a prothrombotic pattern during the first six months of use, and that its use is associated with a reduction in thrombin generation.

Asynchronous expression of myeloid antigens in leukemic cells in a PML/RARalpha transgenic mouse model.

Acute promyelocytic leukemia (APL) is characterized by the expansion of blasts that resemble morphologically promyelocytes and harbor a chromosomal translocation involving the retinoic acid receptor alpha (RARalpha) and the promyelocytic leukemia (PML) genes on chromosomes 17 and 15, respectively. The expression of the PML/RARalpha fusion gene is essential for APL genesis. In fact, transgenic mice (TM) expressing PML/RARalpha develop a form of leukemia that mimics the hematological findings of human APL. Leukemia is diagnosed after a long latency (approximately 12 months) during which no hematological abnormality is detected in peripheral blood (pre-leukemic phase). In humans, immunophenotypic analysis of APL blasts revealed distinct features; however, the precise immunophenotype of leukemic cells in the TM model has not been established. Our aim was to characterize the expression of myeloid antigens by leukemic cells from hCG-PML/RARalpha TM. In this study, TM (N = 12) developed leukemia at the mean age of 13.1 months. Morphological analysis of bone marrow revealed an increase of the percentage of immature myeloid cells in leukemic TM compared to pre-leukemic TM and wild-type controls (48.63 +/- 16.68, 10.83 +/- 8.11, 7.4 +/- 5.46%, respectively; P < 0.05). Flow cytometry analysis of bone marrow and spleen from leukemic TM identified the asynchronous co-expression of CD34, CD117, and CD11b. This abnormal phenotype was rarely detected prior to the diagnosis of leukemia and was present at similar frequencies in hematologically normal TM and wild-type controls of different ages. The present results demonstrate that, similarly to human APL, leukemic cells from hCG-PML/RARalpha TM present a specific immunophenotype.

Asynchronous expression of myeloid antigens in leukemic cells in a PML/RARalpha transgenic mouse model

Acute promyelocytic leukemia (APL) is characterized by the expansion of blasts that resemble morphologically promyelocytes and harbor a chromosomal translocation involving the retinoic acid receptor a (RARa) and the promyelocytic leukemia (PML) genes on chromosomes 17 and 15, respectively. The expression of the PML/RARa fusion gene is essential for APL genesis. In fact, transgenic mice (TM) expressing PML/RARa develop a form of leukemia that mimics the hematological findings of human APL. Leukemia is diagnosed after a long latency (approximately 12 months) during which no hematological abnormality is detected in peripheral blood (pre-leukemic phase). In humans, immunophenotypic analysis of APL blasts revealed distinct features; however, the precise immunophenotype of leukemic cells in the TM model has not been established. Our aim was to characterize the expression of myeloid antigens by leukemic cells from hCG-PML/RARa TM. In this study, TM (N = 12) developed leukemia at the mean age of 13.1 months. Morphological analysis of bone marrow revealed an increase of the percentage of immature myeloid cells in leukemic TM compared to pre-leukemic TM and wild-type controls (48.63 ± 16.68, 10.83 ± 8.11, 7.4 ± 5.46 percent, respectively; P < 0.05). Flow cytometry analysis of bone marrow and spleen from leukemic TM identified the asynchronous co-expression of CD34, CD117, and CD11b. This abnormal phenotype was rarely detected prior to the diagnosis of leukemia and was present at similar frequencies in hematologically normal TM and wild-type controls of different ages. The present results demonstrate that, similarly to human APL, leukemic cells from hCG-PML/RARa TM present a specific immunophenotype.