Factor VII (FVII) deficiency is a rare haemorrhagic condition, normally inherited as an autosomal recessive trait, in which clinical presentation is highly variable and correlates poorly with laboratory phenotype. The FVII (F7) gene was sequenced in 48 unrelated individuals with FVII deficiency, yielding a total of 23 novel lesions including 15 missense mutations, 2 micro-deletions, 5 splice junction mutations and a single base-pair substitution in the 5' untranslated region. Family studies were performed in order to distinguish the contributions of individual mutant F7 alleles to the clinical and laboratory phenotypes. Specific missense mutations were evaluated by molecular modelling in the context of the FVIIa-tissue factor crystal structure. Single base-pair substitutions in splice sites and the 5' untranslated region were studied by in vitro splicing assay and luciferase reporter gene assay, respectively. All probands were also typed for four previously reported F7 polymorphisms. In the majority of cases of FVII deficiency studied here, consideration of both mutational and polymorphism data permitted the derivation of plausible explanations for the FVII activity and antigen levels measured in the laboratory. Inter-familial variation in FVII activity and the antigen levels of heterozygous relatives of probands was found to be significantly higher than intra-familial variation, consistent with the view that the nature of the F7 gene lesion(s) segregating in a given family is a prime determinant of laboratory phenotype. Although no relationship could be discerned between laboratory phenotype and polymorphism genotype, the frequencies of the A2 and M2 polymorphic alleles were significantly higher in the FVII-deficient individuals tested than in controls. This suggests that the presence of these alleles may have served to increase the likelihood of pathological F7 gene lesions coming to clinical attention.

Inherited factor VII (FVII) deficiency is considered to be a haemorrhagic disease. Nonetheless, some patients paradoxically present with venous thrombosis. We assessed whether there was a link between phenotype and genotype in seven patients with inherited FVII deficiency and thrombosis (eleven venous thrombotic events). For each patient (FVII:C < 50%), clinical data were collected, aetiological assessment of risk factors for thrombosis was investigated, and direct sequencing of the nine exons and promoter of the FVII gene (F7) was performed. We present the second series ever published on FVII patients with thrombosis. In nine of the eleven thrombotic events, there was at least one classical triggering risk factor; clinical (n = 4), familial antecedent (n = 2), or biological, defined by phospholipid-binding antibodies or elevated FVIII:C levels (n = 7). In contrast to a previous series, only two events occurred after surgery, performed both with and without replacement therapy. The thrombotic event remained unexplained in one young patient, highlighting the lack of 'protection' against venous thrombosis by low FVII:C levels. Genetic mutations were found to be heterogeneous. Among the seven F7 sequence alterations identified in the present study, only two (p.Ala354Val and p.Arg364Gln) have previously been reported in FVII-deficient patients presenting with venous thrombosis. Our genetic analyses of the F7 mutations in these patients show the complexity of FVII deficiency associated with thrombosis. These data justify a holistic, clinical and biological approach for patients with these specific symptoms. This series also strongly suggest that mild FVII deficiency should not prevent physicians from using antithrombotic prophylaxis in FVII-deficient patients.

Factor X deficiency is a rare haemorrhagic condition, normally inherited as an autosomal recessive trait, in which a variable clinical presentation correlates poorly with laboratory phenotype. The factor X (F10) genes of 14 unrelated individuals with factor X deficiency (12 familial and two sporadic cases) were sequenced yielding a total of 13 novel mutations. Family studies were performed in order to distinguish the contributions of individual mutant F10 alleles to the clinical and laboratory phenotypes. Missense mutations were studied by means of molecular modelling, whereas single basepair substitutions in splice sites and the 5' flanking region were examined by in vitro splicing assay and luciferase reporter gene assay respectively. The deletion allele of a novel hexanucleotide insertion/deletion polymorphism in the F10 gene promoter region was shown by reporter gene assay, to reduce promoter activity by approximately 20%. One family manifesting an autosomal dominant pattern of inheritance possessed three clinically affected members who were heterozygous for a splice-site mutation that was predicted to lead to the production of a truncated protein product. A model which accounts for the dominant negative effect of this lesion is presented. Variation in the antigen level of heterozygous relatives of probands was found to be significantly higher between families than within families, consistent with the view that the nature of the F10 lesion(s) segregating in a given family is a prime determinant of the laboratory phenotype. By contrast, no such relationship could be discerned between laboratory phenotype and polymorphism genotype.

Excessive apoptosis is implicated in the pathogenesis of myelodysplastic syndromes (MDS). We assessed by flow cytometry the expression of several members of the Bcl-2 family in bone marrow mononuclear cells (BMMNC) of 168 MDS samples at diagnosis. The proteins studied were Bcl-2, Bcl-xL (anti-apoptotic), Bax, Bad, Bak, and Bcl-xS (pro-apoptotic). The percentage of BMMNC expressing Bcl-2 and Bcl-xL was higher in refractory anemia with excess of blasts (RAEB), RAEB in transformation (RAEB-T), and chronic myelomonocytic leukemia (CMML) than in refractory anemia (RA) and RA with ringed sideroblasts (RAS). Conversely pro-apoptotic proteins Bad, Bak, and Bcl-xS were detected in a higher percentage of cells in RA and RAS. RA and RAS were associated with an increased Bcl-xS/Bcl-xL ratio. The expression of anti-apoptotic proteins was also correlated with that of CD34 and P170 and with the percentage of blast cells. Two-color analyses demonstrated that CD34 and Bcl-2 were usually expressed in the same cells. No significant correlation was found with cytogenetic abnormalities. Higher expression of pro-apoptotic Bcl-2-family proteins (Bak, Bad, Bcl-xS) and higher Bcl-xS/Bcl-xL ratio were associated with longer survival and decreased risk of leukemic transformation in univariate analysis, whereas expression of anti-apoptotic proteins was associated with decreased survival. Consequently Bcl-2 proteins expression was well correlated with the International Prognostic Scoring System (IPSS). Our data confirm that the control of apoptosis is deregulated in MDS cells. Moreover, the study of markers such as CD34 (or Bcl-2), Bcl-xL, and Bcl-xS provides additional prognostic information.

We report six cases of protein S deficiency secondary to varicella. Five cases were complicated by thrombotic and vascular events, namely purpura fulminans and necrotic vasculitis, deep vein thrombosis and stroke. Two cases were associated with protein C deficiency and one case revealed a heterozygous factor XII deficiency. The underlying mechanism of this acquired protein S deficiency is unclear but could be related to a direct effect of zoster virus.