SummaryFactor VII (FVII) is a four-domain glycoprotein that plays a critical role in the initiation of blood coagulation. Hereditary deficiencies of this plasma protein results in a bleeding diathesis that varies in severity amongst affected patients. We have analysed the FVII gene in 27 patients with FVII deficiency from 21 unrelated families predominantly of Middle-Eastern extraction. A total of 19 different mutations were identified, of which 12 were novel and 7 had been previously reported. Nine of the 12 novel mutations were missense mutations located in the Gla domain (Ser23Pro), the second epidermal growth factor domain (Cys135Arg) and the catalytic serine protease domain (Arg247Cys, Arg277Cys, Ser282Arg, Pro303Thr, Ser363Ile, Trp364Cys, Trp364Phe), of which five are homozygous. Three novel splice mutations were identified in intron 1a (IVS1a+5), intron 2 (IVS2+1) and intron 6 (IVS6+1). Of the seven previously reported mutations, five were missense mutations of which three are homozygous (Gln100Arg, Arg152Gln, Arg304Gln, Cys310Phe and Thr359Met), one was a 17 bp deletion (10585del17bp) and one was a splice site mutation within intron 7 (IVS7+7). This study has significantly extended the current database of FVII mutations, including the number of known homozygous mutations. Conformational analyses of crystal structures for FVIIa and the FVIIa-tissue factor complex provided likely explanations for the effect of the missense mutations on FVIIa secretion or function. In particular, since 23 missense mutations were located to the serine protease domain, mostly to the region between the catalytic triad and the contact surface with tissue factor, this showed that the orientation of the serine protease domain relative to bound tissue factor in the complex is crucial for functional activity.

Cystic fibrosis (CF) is characterized by progressive and ultimately fatal pulmonary disease although there are notable variations in clinical features. This heterogeneity is thought to lie outside the cystic fibrosis transmembrane regulator (CFTR) gene locus and may stem from deficiencies in the antiproteinase screen that protects the lung from proteolytic attack. One hundred and fifty seven patients were recruited from two UK CF centres. The serum concentrations of alpha1-antitrypsin, alpha1-antichymotrypsin and C-reactive protein (CRP) were determined and patients were screened for the common S and Z deficiency alleles of alpha1-antitrypsin and the G-->A mutation in the 3' noncoding region of the alpha1-antitrypsin gene (Taq-I G-->A allele). Alpha1-antitrypsin deficiency phenotypes were detected in 20 (16 MS, 1 S and 3 MZ) out of 147 unrelated tested CF patients and were, surprisingly, associated with significantly better lung function (adjusted mean forced expiratory volume in one second (FEV1) 62.5% of predicted for deficient group and 51.1% pred for normal alleles; p=0.043). The Taq-I G-->A allele was found in 21 out of 150 unrelated patients and had no significant effect on CF lung disease or on levels of alpha1-antitrypsin during the inflammatory response. We show here that, contrary to current thinking, common mutations of alpha1-antitrypsin that are associated with mild to moderate deficiency of the protein predict a subgroup of cystic fibrosis patients with less severe pulmonary disease. Moreover, the Taq-I G-->A allele has no effect on serum levels of alpha1-antitrypsin in the inflammatory response, which suggests that the previously reported association of the Taq-I G-->A allele with chronic obstructive pulmonary disease is not mediated by its effect on the serum level of alpha1-antitrypsin.

We have identified a novel polymorphism located in intron 1a of the human factor VII gene, caused by the nucleotide change G to A at position + 73. In a population of 128 healthy individuals from northern Italy, the variant A73 allele had a frequency of 0.21, whereas the frequency of the previously reported 10 bp insertion allele located at -323 in the promoter region was 0.17 and that of the Q353 allele in the catalytic region of the factor VII gene was 0. 20. In 75% of the healthy individuals, the A73 allele was present together with the 10 bp insertion and the Q353 alleles, indicating a strong linkage disequilibrium. The concomitant presence of A73 with both the 10 bp and the Q353 alleles was associated with the lowest factor VII levels, measured as coagulant activity, activated factor VII and factor VII antigen. The G73A polymorphism was also evaluated in 190 survivors of myocardial infarction who had experienced the event before the age of 45 years and in 179 individuals with a negative exercise test matched with patients for sex, age and geographical origin. Patients carrying the A73 allele associated with lower factor VII levels tended to have a lower risk of myocardial infarction (adjusted odds ratio 0.54; 95% confidence intervals 0.29-0.99). In conclusion, we found a novel variant allele in intron 1a of the human factor VII gene that is often associated in healthy individuals with the 10 bp and Q353 alleles in the promoter and catalytic region of the same gene. This intronic mutation, alone or in association with other factor VII gene polymorphisms, might confer protection against myocardial infarction in the young.

No abstract