A3 Haplotype Research Articles

Soluble endothelial protein C receptor (sEPCR) levels and venous thromboembolism in carriers of two dysfunctional protein C variants

The role of the A3 haplotype and soluble endothelial protein C receptor (sEPCR) plasma levels in predisposing the carriers of two peculiar dysfunctional protein C (PC) variants (PC Arg-1→Cys and PC Arg-1→Leu, also known as PC Padua 2 and PC Padua 3, respectively) to venous thromboembolism (VTE) has been evaluated. The levels of sEPCR have been assessed in family members during 6 years of follow-up and correlated to the presence of the A3 haplotype. Individuals who carried both a dysfunctional PC and the A3 haplotype and presenting with high levels of sEPCR experienced severe VTE at young age. The increased plasma levels of sEPCR were not related to excessive thrombin generation. Carriers of the A3 haplotype showed levels of sEPCR above 135 ng/ml (80th percentile of the distribution in healthy subjects), which remained elevated during the follow-up. In non-carriers of the A3 haplotype, sEPCR levels remained persistently around 100 ng/ml or lower. In conclusion, we have observed that elevated sEPCR plasma levels and the concomitant presence of the A3 haplotype of EPCR gene are associated with severe thrombotic manifestations in carriers of two dysfunctional PC variants. Whether high plasma levels of sEPCR and/or the presence of the A3 haplotype increase the risk of thrombosis in carriers of other PC defects or thrombophilic conditions remains to be clarified.

A haplotype of the EPCR gene is associated with increased plasma levels of sEPCR and is a candidate risk factor for thrombosis

AbstractThe endothelial cell protein C (PC) receptor (EPCR) facilitates PC activation by the thrombin-thrombomodulin complex. A soluble form of this receptor (sEPCR) found in plasma inhibits both activated PC (aPC) activity and PC activation by competing for PC with membrane-associated EPCR. Elevated sEPCR levels are found in approximately 20% of healthy subjects, but the mechanisms underlying this interindividual variability are unknown. We measured sEPCR levels in 100 healthy male volunteers, and observed 2 phenotypic groups of subjects. The temporal stability of sEPCR levels suggested genetic control. Extensive analysis of the EPCR gene in these subjects revealed 13 polymorphisms in complete linkage disequilibrium; these defined 3 haplotypes, 1 of which (A3) was strongly associated with high sEPCR levels. The high constitutive sEPCR levels observed in A3 haplotype carriers might reduce the efficiency of the PC system and predispose these subjects to venous thrombosis. By studying 338 patients with venous thrombosis and 338 age- and sex-matched healthy subjects, we found that the A3 haplotype was overrepresented in the patients. In multivariate analysis, subjects carrying the A3 haplotype had an increased risk of thrombosis (odds ratio [OR] = 1.8; P = .004). Thus, the A3 haplotype, which is associated with elevated plasma sEPCR levels, is a candidate risk factor for venous thrombosis.

Novel polymorphisms in the promoter region of the neurotrophin-3 gene and their associations with schizophrenia.

Based on the neurodevelopmental hypothesis in the etiology of schizophrenia, neurotrophic factors may be involved in the pathogenesis of the illness. We searched for polymorphisms in the promoter region of the neurotrophin-3 (NTF3) gene by using denaturing high performance liquid chromatography (DHPLC). Six single nucleotide polymorphisms (SNPs) were found. When these polymorphisms were examined for association with schizophrenia, a weakly significant difference was observed in the genotype distribution of the G/- 3004/A polymorphism between 184 schizophrenics and 185 controls (P < 0.05), although no statistically significant association was detected in a family-based sample of 50 trios (schizophrenics and their parents). With respect to the other polymorphisms, there was no significant association with schizophrenia. The G/- 3004/A polymorphism was in linkage disequilibrium with the CA repeat polymorphism in the first intron of the NTF3 gene. When haplotype-based analysis was performed, an increased frequency of the haplotype containing the G(- 3004) and the "A3" ([CA]23) alleles was observed for the schizophrenics compared to controls. Our results suggest that the G(- 3004)-A3 haplotype has a modest effect of giving susceptibility to schizophrenia.